Male Infertility

Question 1

Oligozoospermia

Answer 1

A low sperm count, also called oligozoospermia, is where a man has fewer than 15 million sperm per millilitre of semen.

Question 2

What is the consequence of most trisomies or autosomal losses of chromosomes?

Answer 2

Embryonic lethality and frequent cause of miscarriages

Question 3

What cuases numerical chromosome defects?

Answer 3

nondisjunction during metaphase of meiosis

Question 4

What is klinefelter syndrome?

Answer 4

Klinefelter Syndrome is one of the most frequent chromosomal anomalies, occurring in about 1 of 500 births. Duplication of the X chromosome occurs most frequently (XXY), however, rarely patients may present with XXXYor XXXXY. More rarely, Klinefelter patients may be mosaic, meaning that some cells will have a normal karyotype while others have an extra X chromosome(s).

usually azoospermic with small atrophic testes, although the phenotype may vary and, rarely, pregnancies have been achieved without assisted reproductive techniques. However, most commonly, the Klinefelter male will be azoospermic, as the presence of the two X chromosomes is incompatible with the completion of meiosis during spermatogenesis. Testicular sperm extraction (TESE) and intracytoplasmic sperm injection (ICSI) have resulted in some pregnancies, but caution is warranted. While the offspring born to date have had normal karyotypes, genetic counseling and prenatal genetic testing is advisable for these couples.

Question 5

What happens with XYY males?

Answer 5

XYY males are usually ferrtile but rarely may present with infertility

Question 6

What are XX males? Can ICSI be used for these patients?

Answer 6

XX Males are genotypic females and phenotypic males. This syndrome is characterized by development of the testes and male genital tract with normal masculinization, but small atrophic testes.

Again, the presence of two X chromosomes blocks meiosis resulting in azoospermia. The majority of these patients have a small piece of the Y chromosome that encodes the SRY or testis determining gene translocated to an X chromosomes.

This gene is sufficient to induce testicular differentiation during embryonic development. Rarely, XX males may have no detectable Y chromosome genes present (no SRY) and in these cases, the phenotype is thought result from an activating mutation of an autosomal gene resulting in sex reversal.
**
ICSI should not be attempted for XX males, as they have a Sertoli cell—only phenotype and sperm will not be retrieved.**

Question 7

when do translocations and deletions often occur?

Answer 7

during crossing-over during meiotic recombination

Question 8

What are the consequences of balanced translocations?

Answer 8

ususally few phenotypic abnormailities
can result in male or female infertility

unbalanced translocation may occur resulting in embryonic lethality and severe birth defects

ICSI has been succcessful using sperm from pateints withy balanced translocations obtained by testicular sperm extraction

Question 9

What are robertsonian translocations? Which chromosomes are typically affected?

Answer 9

well-recognized cause of male infertility. These are the most common translocations, usually between either Chromosomes **13,14 or 14,15 or 13,21 or 21,22, **

because these are all acrocentric chromosomes that may misalign during meiosis and result in the long arm of one chromosome translocated onto the long arm of another chromosome.

The two small fragments resulting may combine but are usually lost resulting in an apparently normal individual with just 45 chromosomes.

These translocations can be balanced, unbalanced, mosaic, or complex, and most carriers of a balanced Robertsonian translocation are phenotypically normal and the chromosome defect undetected until they attempt to reproduce and the males often have oligozoospermia. These individuals have an increased risk of infertility, spontaneous miscarriage, offspring with unbalanced translocations, and uniparental disomy (UPD) or UPD-related imprinting disorders if chromosomes 14 and 15 are involved.

Question 10

Which chromosomes are usually affected by robertsonian translocations?

Answer 10

13/14
14/15
13/21
21/22

Question 11

How is male fertility affected by Robertsonian Translocation?

Answer 11

usually oligozoospermia
increased risk of infertility
spontaneous miscariage
offspring with unbalanced translocations
uniparental disomy (UPD) or UPD-related imprinting disorders if chrosomes 14 and 15 involved

Question 12

What is the AZF?

Answer 12

azoospermia factor region on Y chromosome
Yq11
microdeletions here cause azoospermia

In 1995, David Page’s group identified a spermatogenesis gene DAZ or the “deleted in azoospermia” gene in this region of the Y chromosome

Question 13

What is DAZ?

Answer 13

gene in Yq11
“deleted in azoospermia”

divided into 3 regions: a, b, c

Question 14

Microdeletion of which AZF regions is associated with male infertility?

Answer 14

AZFa/AZFb associated with pure sertoli cell only phenotype. TESE for ICSI should not be done

AZFc have higher likelihood of finding sperm in testis biopsy

Question 15

What is SHOX?

Answer 15

about 12% of men with Y chromosome microdeletions have a co-existing genomic syndrome called SHOX, a gene encoded on the top of the short arm of the X and Y chromosomes (the pseudoautosomal region 1 that undergoes homologous recombination during meiosis). The SHOX gene encodes a protein involved in stature, which when mutated or a copy(ies) are lost
results in stature anomalies and some limb deformaties.

Question 16

How are Y chromosome microdeletions usually identified?

Answer 16

multiplex PCR

Question 17

What is the frequency of Y chromosome deletions in non-obstructive azoospermic men? and severly oligospermic men?

Answer 17

5-15% depending on lab and likely due to patient selection bias

still significant in oligospermic men but less so

Question 18

Are men with Y chromosome microdeletions fertile?

Answer 18

pregnancies have been achieved
females offspring will be normal
male are likely to be infertile as they will inherit the defective Y chromosome from their fathers

Other traits encoded by Y chromosome may also be affected in male offspring

Question 19

What is the significance of TEX11?

Answer 19

Another Example of a Sex Chromosome Microdeletion Causing Spermatogenic Failure: XLinked TEX11 Mutations, Meiotic Arrest and Azoospermia in Infertile Men

A relatively small 99-kb hemizyous loss on chromosome Xq13.2 encompassing 3 TEX 11 gene exons was identified and additional studies of this gene assessing copy number variations (CNVs), as well as damaging mutations showed that TEX 1 1 regulates homologous chromosome synapsis and doublestrand DNA break repair. TEX 1 1 is critical for synaptonemal complex formation and the chiasma in chromosomal crossover and when deficient (CNVs; or when there are damaging mutations) meiosis cannot proceed, and there is a meiotic arrest resulting in non-obstructive azoospermia.

Question 20

What is array comparitive genomic hybridization and what is it used to analyze?

Answer 20

identify CNVs

oligonucleotides arrayed on a glass slide and the patient and reference (control normal) samples are differentially labeled with fluorphors fluorescing red and green. The DNAs are then hybridized to target oligonucleotides (nucleic acids) on the slide. When both concentrations are in equilibrium, the spot fluoresces yellow. A copy number gain in the patient fluoresces green whereas a loss fluoresces red. This is a high-resolution analysis that can analyze an entire genome with a tiling microarray. It can only recognize unbalanced gains or losses (not inversions).

Question 21

What is the function of wilms tumor supressor gene (Wt-1) during gonadal development?

Answer 21

initiates development of the gonads
when absent, gonadal agenesis occurs

Question 22

What is the function of SF-1 during gonadal development?

Answer 22

Steroidogenic factor 1 (SF-1)
orphan receptor
regulator of embryonic gonadal development
development of adrenals

transcription factor regulates expression of downstream genes such as p450 hydroxylases, Dax1, mullerian inhibiting substance

Question 23

What is the importance of WT1 and SF1 during gonadal development?

Answer 23

required for genital ridge formation
SF1 is dosage sensitive and loss of copy can induce sex reversal in XY individuals

Question 24

What happens by the end of 5th week of gestation for gonadal development?

Answer 24

By the end of the 5th week of gestation, the germ cells have arrived at the genital ridge and proliferate. These germ cells are encompassed by the cells forming the seminiferous cords and differentiate into spermatogonial precursors but do not enter the meiotic pathway, unlike the events occurring in the fetal ovary during development. In the absence of germ cell migration to the genital ridge or lack of survival the testis will continue to develop, unlike the fetal ovary, which requires germ cell migration through meiosis (if this does not occur the follicular cells degenerate, and streak gonads develop).

Question 25

What is the master testis determining factor?

Answer 25

SOX9

SRY is the testis determining factor because it upregulates SOX9 gene expression and the transcription factor SOX9 is now considered by many to be the master testis determining factor. Thus, SRY, which tilts the balance between testis and ovarian directing gene expression, **is necessary but not sufficient for testis determination **and both the timing of expression and the level of expression are critical factors

SOX9 either succeeds in determining Sertoli cell differentiation or is silenced by other genes that enact ovarian differentiation—it is a true battle of the sexes! It is important to be aware that there are a number of genes that must be expressed during early fetal gonadal sexual differentiation to effectively elicit the development of a functional testis or ovary (Figure 13), but for the purposes of this course, the take home message is that both SR Y and SOX9 actions are required for testis differentiation.

Question 26

What can cause XX or XY individuals to have reproductive organs or external genitalia of the opposite sex?

Answer 26

small fragment of Y chromosome that includes SRY is present in XX individual
or loss/mutated SRY that doesnt signal the initial step of testis determination

Question 27

What happens when one copy of SOX9 is lost in XY individuals?

Answer 27

disorder of sexual determination
haploinsufficiency can result in XY sex reversal with campomelic dysplasia

Campomelic dysplasia is a severe genetic disorder that affects development of a baby’s airway, lungs, bones and reproductive organs. The condition is a type of osteochondrodysplasia, which causes several types of short stature (dwarfism) involving abnormal bone and cartilage growth

Question 28

What can SOX9 duplication cause in XX individuals?

Answer 28

XX sex reversal
46, XX testicular or 46, XX votesticular DSD

Ovotesticular disorder of sex development (ovotesticular DSD) is a very rare disorder in which an infant is born with the internal reproductive organs (gonads) of both sexes (female ovaries and male testes). The gonads can be any combination of ovary, testes or combined ovary and testes (ovotestes). The external genitalia are usually ambiguous but can range from normal male to normal female.

Question 29

Defects in which systems can cause disorders of sexual development?

Answer 29

In general, defects that affect the hypothalamic-pituitary axis, steroid biosynthesis, steroid metabolism, steroid hormone receptor action, protein hormones, and their receptors, as well as other major developmental signaling pathways and their receptors (WNT, FGFs, RETT, cell polarity, RNA splicing, growth factors, ion channels, etc.) can underlie these birth defects—and the cause of many remain unknown but are active areas of investigation

Question 30

What are hypospadias? And what is the incidence?

Answer 30

Hypospadias is abnormal anterior urethral development where the urethral opening is proximal to the tip of the glans penis. The urethral opening can be anywhere from malpositioned on the glans of the penis to the mid-shaft region, or at the scrotum or perineal regions in the more severe forms of the defect. This birth defect is common, occurring in about 1:300 male births. Over 1,400 different genes have been implicated in hypospadias with varying degrees of evidence

1/300 male births

Question 31

What is cryptorchidism? and its incidence?

Answer 31

affecting about 3% of boys by the age of 6 months. This is failure of testicular descent, which presents a risk of infertility as well as carcinogenesis. Known genetic defects associated with this birth defect are defects in steroid biosynthesis, metabolism, androgen receptor function, the Ins13 gene and Lgr8 growth factor receptor for Ins13

nearly 2500 different genes have been implicated to date in causing cryptorchidism, again, with varying degrees of evidence; some of these cases are syndromic (multiple organs affected), but the majority are isolated failure of testicular descent. Cryptorchidism is important male reproductive birth defect to know because it is a significant cause of male infertility, even when the testis is placed into the scrotum during infancy, the majority of men have infertility due to spermatogenic failure, and they are at an elevated risk of testis cancer development

Question 32

What is CBAVD and mutations in which gene are associated with it?

Answer 32

Congenital Bilateral Absence of the Vas Deferens (CBA VD): We now know that patients with CBAVD have a genital form of cystic fibrosis resulting from mutation of the cystic fibrosis fransmembrane regulatory gene (CFTR). Over 1300 different mutations have been identified in this gene, many of which cause cystic fibrosis.

Before the etiology of CBAVD was understood, assisted reproductive techniques such as microsurgical epididymal sperm aspiration with in vitro fertilization (more recently with ICSI) used to treat the vasal agenesis patients resulted in the birth of several children suffering from cystic fibrosis

Ideally, mutation analysis of the cystic fibrosis gene (cystic fibrosis transmembrane conductance regulator protein, CFTR) should be performed on both the patient with CBAVD and his partner.

Because there are over 1300 known mutations in this gene, as well as a polymorphism of the 7T allele in intron 8 (the 5T allele that qualitatively and quantitatively influences the production of CFTR), all patients with CBAVD are now thought to have a genetic form of cystic fibrosis.

Question 33

Why should a second diagnostic analysis of 5T allele of CFTR gene be requested?

Answer 33

For the CBAVD patients, a second diagnostic analysis of the CFTR gene must be requested for the 5T allele, and this is not routinely run in many clinical laboratories performing routine cystic fibrosis gene analysis. The 5T allele (a polymorphic region ofthymidines in intron 9 of the CFTR gene) results in less efficient processing of the CFTR mRNA resulting in a lower amount of protein present and increases the severity of the phenotype observed. Again, a laboratory result of no mutations identified does not ensure that no mutation is present as the CFTR gene is large, and currently available testing does not analyze the whole gene. These couples require genetic counseling and prenatal genetic diagnosis to ensure that they understand the risks of conceiving an offspring affected with cystic fibrosis.

Question 34

What is the significance of X-linked ADGRG2?

Answer 34

There is now a second gene, X-Iinked ADGRG2 (Adhesion G Protein-Coupled Receptor G2) that, when mutated, gives a phenotype indistinguishable from CBAVD due to CFTR mutations. Thus, to date there are just two genes that when mutated cause CBAVD.

Question 35

What do defects in AMH/MIH cause?

Answer 35

defects result in males with oviducts, a uterus and vagina together with a complete male reproductive system.

Testicular descent is prevented by the presence of the remnants of the müllerian derivatives.

Question 36

What is hypogonadotropic hypogonadism? Kallmann syndrome?

Answer 36

Kallmann Syndrome is due to failure of the GnRH-releasing neurons to migrate to the olfactory lobe during development. It is an X-Iinked disorder and the gonadotropins are not produced.

Question 37

What is androgen insensitivity syndrome?

Answer 37

Defects in either the genes involved in the biosynthesis or metabolism of androgens or in the receptors themselves can have profound effects on male sexual development and function. Androgen receptor mutations or deletions can result in complete androgen insensitivity syndrome (resulting from total inactivation of the androgen receptor)

with a female external genitalia and testis present internally or partial androgen insensitivity.

Question 38

What do mutations in PIAS cause?

Answer 38

protein that regulates transcription in mammals. PIAS proteins act as transcriptional co-regulators with at least 60 different proteins in order to either activate or repress transcription. The transcription factors STAT, NF-κB, p73, and p53 are among the many proteins that PIAS interacts with.

Protein inhibitor of activated STAT (PIAS) results in a spectrum of phenotypic defects ranging from an under-virilized male who is fertile to patients with Reifenstein syndrome who are infertile. Polymorphisms in exon 1, the portion of the receptor responsible for transactivation, have been found with greater frequency in azoospermic and oligospermic patients. These polymorphisms exhibit lower functional activity of the androgen receptor although the exact mechanism of this polymorphism action on male fertility is not understood. Testing for these polymorphisms is not routinely performed in clinical laboratories. It is important to realize that endocrine causes of male infertility are relatively rare, accounting for about 1% of all male infertility, so androgen receptor mutations are a relatively rare cause of male infertility

Question 39

What is virilization?

Answer 39

Virilization or masculinization is the biological development of adult male characteristics in young males or females.[1] Most of the changes of virilization are produced by androgens.

In common as well as medical usage, virilization often refers to the process of normal male puberty. These effects include growth of the penis and testes, accelerated growth, development of pubic hair, and other androgenic hair of face, torso, and limbs, deepening of the voice, increased musculature, thickening of the jaw, prominence of the neck cartilage, and broadening of the shoulders.

Question 40

What is undervirilization?

Answer 40

Undervirilization can occur if a genetic male cannot produce enough androgen or the body tissues cannot respond to it. Extreme undervirilization occurs when no significant androgen hormones can be produced or the body is completely insensitive to androgens. Both result in a female body. Partial undervirilization produces ambiguous genitalia part-way between male and female. The mildest degree of undervirilization may be a slightly small penis. Examples of undervirilization are androgen insensitivity syndrome, 5 alpha reductase deficiency, and some forms of congenital adrenal hyperplasia.

Question 41

What is reifenstein syndrome? what are the symptoms?

Answer 41

A syndrome characterized by hypogonadism as a result of a defect in androgen receptor. Often described as the male pseudohermaphrodism, presenting with hypospadias, gynecomastia, normal XY karyotype, and a pattern X-linked recessive inheritance.

Partial Androgen Insensitivity; Gynecomastia-Hypospadias Syndrome; Hereditary Familial Hypogonadism; Male Pseudohermaphroditism.

Two types have been suggested: Type I refers to the familial incomplete male pseudohermaphrodism and Type II is the autosomal recessive.

X-linked recessive.

Underlying defect is the partial deficiency of androgen receptors (AR), causing partial androgen resistance, and not because of a lack of androgen synthesis.

Clinical features (hypogonadism); family history; elevated plasma luteinizing hormone and testosterone levels; oligospermia or azoospermia; testis biopsy show normal Leydig and Sertoli cells but immature germinal cells and no spermatozoa; cultured fibroblast from genital skin show reduced levels of androgen receptor present with decreased cytoplasmic dihydrotestosterone binding capacity. The normal chromosomal study (46,XY) and normal testosterone conversion enzyme study (particularly 5-reductase level) exclude other causes of androgen resistance.

The phenotype is quite variable as a consequence of the partial sensitivity of the androgen receptors. In its mildest form, the man is infertile but otherwise normal. In its most severe form, the male pseudohermaphrodite may have hypospadias, cryptorchism, bifid scrotum, microphallus, atrophic ectopic testes, pseudovagina, gynecomastia, and absent vas deferens. Axillary and pubic hair is usually normal but chest and facial hair are minimal. Temporal recession of hairline is minimal and the voice is prepubertal in character. Azoospermia is common and occasionally accompanied by hypoplasia of vas deferens. Most have a male psychological development. Germ cell malignancies can occur.

Question 42

Approximately how many genes have an identified association with male infertility?

Answer 42

In short, thousands of genes have been identified that, when deleted or mutated, result in male infertility, and it is estimated that thousands are involved in all aspects of male fertility. In GeneCards more than** 2,900 **genes are now associated with human male infertility. Indeed, a number of gene defects that underlie defects in genitourinary development, spermatogenesis, the control of the hypothalamic-pituitary-gonadal axis, spermiogenesis, genital tract function, sperm function and events required for fertilization were identified in infertile men, although the frequency of each type of defect in general appeared rare.

Question 43

How frequent are abnomral karyotypes in patients with idopathic infertility?

Answer 43

7-13%

Question 44

How and when is a karyotype performed?

Answer 44

A karyotype analysis is routinely performed in most genetics laboratories. Blood is drawn in a green top tube, and the white cells are isolated and placed in culture together with a mitogen to stimulate their proliferation. Colchicine is administered to disrupt microtubules to arrest the cell cycle in metaphase where the chromosomes are visible. The cells are placed into a hypotonic buffer and placed onto the microscopic slide, where they burst spreading the chromosomes. After staining (sometimes with Giemsa; more advanced labs may use chromosome specific fluorescent probes), the slides are manually analyzed by the cytogeneticist for chromosome number, banding patterns and structure

As this is a significant association with male infertility, high-resolution banding cytogenetic analysis is now routinely ordered during the evaluation of the idiopathic infertile male contemplating the application of an assisted reproductive technique, especially if sperm densities fall below 5 million/mL.

Question 45

How are Y chromosome microdeletions usually analyzed? Which microdeletions are associated with TESE sperm?

Answer 45

Laboratories employ a variety of approaches to analyze the Y chromosome for microdeletions. Usually, a multiplex PCR assay is employed to amplify specific regions of the Y chromosome. The amplified DNA fragments are then electrophoresed and stained with ethidium bromide to visualize the PCR fragments. Although the sequence tagged sites analyzed may vary between laboratories, the test should include those that span interval 6, the AZFa, b and c regions and other regions thought to encode putative spermatogenesis genes. The multiplex PCR reaction should be tested with both positive and negative controls (normal male and female DNA) and should contain a positive marker for the Y chromosome (usually the SR Y gene) (Figure 16). There is no standardization of this test, and accordingly, many of the commercially available tests do not cover all of the required regions that inform clinical decision making. Knowledge of which regions of the Y chromosome are microdeleted is critical.

**Although sperm can usually be found using microTESE in about % of men with isolated AZFc deletions. **In contrast, deletion of AZFa
and/or AZFb portends an extremely small likelihood of finding a sperm on microTESE (Hopps et al., 2003). Indeed, the literature shows that men with AZF a and/or b deletions and those with Yq deletions should be counselled to seek other routes to parenthood as these men are not candidates for TESE-ICSI because no rare sperm will be found.

Question 46

In which patients should CFTR be analyzed for mutations?

Answer 46

All patients with congenital bilateral absence of the vas deferens (CBAVD) and their spouses should be analyzed for mutations in the cystic fibrosis transmembrane regulatory (CFTR) gene, as well as the presence of the 5T allele. If cost is a concern, the male CBAVD patient is considered to be positive for CFTR mutations, and the female partner must be analyzed.

Routine analysis of the CFTR gene is available from most genetic laboratories, however, these tests focus on 30-45, perhaps 90, of the most common mutations causing cystic fibrosis, not CBAVD. Accordingly, a negative finding with these tests does not ensure that mutations are not present.

Question 47

What is the X-linked form of CBAVD?

Answer 47

Importantly, a recent publication identified truncating mutations in the adhesion G protein-coupled receptor G2 gene (ADGRG2) causing an X-Iinked form of CBAVD that is phenotypically indistinguishable from that caused by CFTR mutations (Patat et al., 2016). A subset of these infertile men had a unilateral kidney in addition to confirmed CBAVD and ADGRG2 damaging mutations.

In the approximately 20% of men with CBAVD who are CFTR-mutation negative, kidney ultrasound and ADGRG2 testing will allow appropriate genetic counseling given the X-Iinkage of this genetic defect.

Question 48

What is FISH? why is it performed? and when?

Answer 48

In the germ cells of some infertile patients with a normal somatic karyotype, an increase in chromosome aneuploidy is found with possible implications for their offspring

In this assay, fluorescently labeled probes specific to chromosomes 13, 18, 21, X, and Y are hybridized to the sperm and analyzed. Haploid cells (sperm) should have 1 of each autosomal chromosome and either an X or Y sex chromosome.

These chromosomes are the only ones that are consistent with a viable but affected offspring.

Indeed, the test is particularly useful in couples with recurrent pregnancy loss.

Some of these men have extremely high levels of aneuploid sperm in their ejaculate, despite having relatively normal semen parameters.

Others at risk of increased levels of sperm aneuploidy are men with severe oligozoospermia, oligoasthenoteratozoospermia, and cryptozoospermia/non-obstructive azoospermia (Ramasamy et al., 2014; Ramasamy et al., 2015). FISH analysis of aneuploidy in sperm can be ordered from some specialty laboratories.

Question 49

Which chromosomes are usally tested using FISH?

Answer 49

13,18,21,X,Y
These chromosomes are the only ones that are consistent with a viable but affected offspring.

Question 50

What types of male factor demonstrate high levels of aneuploid sperm?

Answer 50

useful in couples with recurrent pregnancy loss
sometimes can be seen with otherwise normal semen parameters

severe oligozoospermia, oligoasthenoteratozoospermia and cryptozoospermia/non-obstructive azoospermia also at risk of increased levels of sperm aneuploidy

Question 51

what is teratozoospermia?

Answer 51

Teratozoospermia is characterized by the presence of spermatozoa with abnormal morphology over 85 % in sperm. When all the spermatozoa display a unique abnormality, teratozoospermia is said to be monomorphic.

Question 52

What is globozoospermia? what are some associated mutations?

Answer 52

Globozoospermia, the absence of the acrosome or a misplaced or atrophied acrosome, results in a morphological defect that is readily identifiable with a routine semen analysis, a round-headed sperm

SPATA16 (spermatogenesis associated protein 16) is associated with the Golgi apparatus and the proacrosomal vesicles that ultimately fuse to form the acrosome. It is highly expressed in human testis and damaging mutations were identified in a significant percentage of globozoospermic men.

DPY19L2 exhibits either copy number variations (CMVs; gene dosage changes) or damaging mutations that are more common in some different geographic and ethnic regions who show mainly type I globozoospermia with a high percentage of abnormal sperm. From an evidenced based medicine perspective, strong studies on the presence of globozoospermia on ICSI outcomes are few. However, in cases of globozoospermia, there is reduction or absence of phospholipase C zeta (PLCz), a protein required for oocyte activation. Although artificial oocyte activation with calcium ionophore may overcome this deficiency, the live birth rate per transfer remains lower for globozoospermic couples then for others treated with ICSI-IVF (reviewed in Coutton, Escoffier, Martinez, Arnoult, & Ray, 2015).

Question 53

Can globozoospermia be used for IVF?

Answer 53

there is reduction or absence of phospholipase C zeta (PLCz), a protein required for oocyte activation. Although artificial oocyte activation with calcium ionophore may overcome this deficiency, the live birth rate per transfer remains lower for globozoospermic couples then for others treated with ICSI-IVF

Question 54

What is macrozoospermia?

Answer 54

: Sperm from men with macrozoospermia (large headed sperm) show varying degrees of polyploidy and aneuploidy. The degree of polyploidy is inconsistent as haploid may range from 0%-10.9%, diploid from 19.8%-60%, triploid from 10%-62.4% and tetraploid from 5.1%-36%. Some individuals are apparently mosaic with the percent of euploid sperm correlating with the ratio of their normal sized gametes (reviewed in Coutton et al., 2015).
**
The cause of this defect is chromosome nondisjunction or cytokinesis errors occurring during either or both of the meiotic divisions.**

Macrozoospermic sperm should not be injected into an ova with ICSI-IVF as the sperm have varying states of polyploidy.

Question 55

What is the significance of aurora kinase C (AURKC) in male infertility? What abnormal sperm morphology is it associated with?

Answer 55

AURKC is mainly expressed in the spermatocyte (and oocytes), where it ensures the bipolar attachment of the chromosomal diads during meiosis, participates in the meiotic spindle checkpoint, and also plays a role in cytokinesis needed for the second meiotic division

mutation causes severe teratozoospermia - macrozoospermia

causes large-headed mutliflagellated tetraploid sperm

meiosis and cytokinesis cannot properly occur

When mutated, there is premature chromosome segregation, and cytokinesis is blocked during meiosis, resulting in large headed multitailed sperm formation. One particular mutation of this gene, c. 144delC is common in men of European and North African origin with macrozoospermia.

ICSI-IVF is not recommended

Question 56

What is asthenozoospermia?

Answer 56

Asthenospermia is defined as <40% sperm motility or less than 32% with progressive motility.

Question 57

What is primary ciliary dyskinesia (PCD)?

Answer 57

Primary Ciliary Dyskinesia (PCD) is a genetic syndrome with a variety of clearly identifiable symptoms including recurrent respiratory tract infections with varying symptoms ranging from chronic rhinosinusitis to bronchiectasis, varying rates ofhydrocephalus, situs inversus due to organ laterality anomalies that occur during embryogenesis and male infertility due to immotile sperm. It results from motility defects of motile cilia and flagella. With the advent of whole genome and whole exome sequencing and clearly defined family pedigrees, in the past 5+ years, nearly 90 new gene defects causing PCD have been identified, with numerous different loss of function mutations for each gene.

These genes encode proteins required for the structure of the components of motile cilia and flagella—i.e., the inner and outer dynein arms, nexin links, radial spokes, axoneme, peripheral doublets, and so on (see Figure 13 and Figure 9, Chapter 4). In these patients, sperm are viable but totally immotile, and ICSI can be successfully employed but couples should be referred for genetic counseling and the need for genetic evaluation and PGD or PGS.

Question 58

What is MMAF in male infertility?

Answer 58

sperm flagellar defects

Multiple Abnormalities of the Sperm Flagella (MMAF) in Male Infertility: (reviewed in Wang, Tu, & Tan, 2019) MMAF (a cause of asthenoteratozoospermia) was first recognized morphologically nearly 40 years ago, although until the advent of strict criteria for assessment of sperm morphology during the routine semen analysis (World Health Organization, 2010), it was
rarely diagnosed. The presence of severe flagellar abnormalities (absent, short, bent/misaligned, coiled, and irregularly shaped flagella) together with sporadically occurring head anomalies and severe motility defects define this condition

The condition is complex with a high frequency of mutations in dynein axonemal heavy chain 1 (DNAHI), cilia and flagella associated protein 44 (CFAP44), and CFAP43 (these three protein defects account for about 1/3 of MMAF cases) with mutations involving adenylate kinase 7 (AK7), cilia and flagella associated protein 69 (CFAP69), centrosomal protein 135 (CEP135), akinase anchoring protein 3 (AKAP3) or a-kinase anchoring protein 4 (AKAP4)

When loss of function mutations are present, these defective genes encode proteins involved in structural defects of the centriole assembly, peri-axenome structure and the axenome affecting the proximal centriole, the 9 + 2 central pairs of microtubules, the fibrous sheath and outer dense fibers, mitochondrial sheath, outer and inner dynein arms, radial spokes, and nexindynein regulation complex

Question 59

What are the general classes of sperm defects with genetic causes?

Answer 59

1. Primary Ciliary Diskinesia- totally immotile sperm
2. MMAF (flagella- central microtubules)- severe flagellar abnormalities, sporadic head anomales and severe motility defects
3. Displasia/disorganization of the fibrous sheath
4. Annulus Dysfunction
5. Ion Channel Defects
6. globozoospermia

Question 60

Why are sperm centrosomes important during fertilization?

Answer 60

The sperm centrosomes are important during fertilization because the sperm aster formation is required for the sperm and ova pronuclei to unite, control syngamy, and complete the first few mitotic divisions.

when the sperm flagella has structural anomalies, gonosomal disomies and diploidies may occur that ultimately results in nondisjunction and sperm aneuploidies

Depending upon the type of flagellar defect (i.e., anomalies of the axonemal central structures), the embryos created have slower kinetics of*cleavage and lower implantation rates then embryos derived from sperm lacking these structural anomalies. Lower sperm aster formation as a result of defects in the centrosomal or pericetrosomal proteins can diminish the rate of early embryo development, although data in human embryos is lacking to support this.

Question 61

Does normal sperm morphology by strict criteria or normal semen paramters predict sperm chromosomal aneuploidy?

Answer 61

sperm morphology, in general, is not necessarily predictive of a normal chromosomal complement.

Sperm aneuploidy can be highly elevated in a subset of men with normal morphology sperm who are partners in recurrent pregnancy loss couples

a diagnosis of normal sperm morphology using strict criteria does not necessarily portend a normal chromosomal complement

Exception: macroglobozoospermia

Question 62

How do success rates with globozoospermia compare with other forms of male infertility?

Answer 62

, globozoospermic patients undergoing ICSI-IVF have low fertilization, pregnancy, and live birth rates. For some of these globozoospermic patients, fertilization failure is thought to result from the reduction or absence of phopholipase C zeta, a testis-specific protein required for oocyte activation. While artificial oocyte activation may improve fertilization, the live birth rate for men with DPY19L2 or other gene defects underlying this morphological defect is generally lower than other outcomes of ICSI to treat other forms of male infertility although well-powered studies of birth rates for men with well-defined DPY19L2 or SPTAI 6 mutations or CNVs have not been performed.

Question 63

List a few genes associated with globozoospermia (eg acrosome biogenesis)

Answer 63

1. SPATA16
2. DPY19L2
3. SPACA1

Question 64

Can klinfelter syndrome patients produce offspring?

Answer 64

TESE may identify of spermatogenic cells and sperm

children conceived this way have been normal and without klinfelter

rare foci may have corrected themselves and lost an extra X chromosome

Question 65

Can sperm be found in XX individuals?

Answer 65

no because the Y chromosome genes are required for spermatogenesis

testis determination can still occur but without germ cells

Question 66

Does gonadal dysgenesis have sperm?

Answer 66

sperm will not be present