Biological Basis of Impaired Fertility in Males

Question 1

what % of couples globally are affected primarily or contributingly by male infertility

Answer 1

4-6%

Question 2

what can male infertility be classified as

Answer 2

• primary
• secondary

Question 3

3 causes of male infertility subcategories

Answer 3

• congenital
• acquired
• idiopathic (unknown reason)

Question 4

what are some causes of congenital factors of male infertility
what are they mostly caused by

Answer 4

• congenital factors of male infertility are mostly caused by genetic causes
  common genetic causes of infertility
• congenital bilateral absence of vas deferens associated with CF mutation
• Kallmann syndrome
• chromosome abnormalities such as Klinefelter syndrome
• Y-chromosome microdeletions
• anorchia (absence of testes => can’t produce sperm)
• cryptorchidism (testes undescended, present in lower abdominal cavity)
• Robertsonian translocation
• Androgen Insensitivity Syndrome (ie/ intersex)
• obstruction (in testes or in epididymis)
• genetic endocrinopathy

Question 5

[acquired factors] what is most common correctable cause of infertility & what % of infertility cases can it occur in
(is an acquired factor)

Answer 5

• varicocele
  ~40% of all cases

Question 6

what is varicocele

Answer 6

• enlargement of vein within scrotum that supplies testes
  -> leading to reduced sperm concentration and quality

Question 7

what are some acquired factors for male infertility (ie/ contribute to modifications in sperm production)

Answer 7

• direct trauma to testes
• testicular torsion
• germ cell tumours (within testes) (-> cause reduced sperm counts)
• recurrent urogenital (both urinary and genital organs) infections (-> can cause obstruction in epididymis)
• hypogonadotrophic hypogonadism
• inflammatory conditions (ie/ mumps, epididymitis)
• medications / chemotherapy
• systemic disease (ie/ metabolic syndrome, renal failure, autoimmunity)
• sexual dysfunction (this one not sperm modification but reduce ability of male to perform sexual intercourse) (eg/ erectile dysfunction)

Question 8

what % of male infertility is caused by congenital factors

Answer 8

15%

Question 9

what is the largest factor and up to _% of infertility cases in males

Answer 9

• idiopathic factors
• 50% of all cases

Question 10

many __________ and _____ factors contribute to idiopathic causes (even though called unknown causes) of male infertility by reducing sperm quality and _________ _______ in males

Answer 10

• environmental factors
• ## lifestyle factors
• hormone regulation

Question 11

stat of how many men will suffer from infertility in their life time _ in _

Answer 11

1 in 10

Question 12

define primary male infertility

Answer 12

• the male has never been able to father a child

Question 13

define secondary male infertility

Answer 13

• the male has been able to previously father a child, but can no longer

Question 14

what does absence of vas deferens result in mechanically

Answer 14

• sperm unable to transit between testes and penis at ejaculation
  (note: sperm made in testes -> sperm stored and mature in epididymis -> travel along vas deferens -> to ejaculatory duct -> that empties into urethra (at ejaculation)
  (sperm mixed with various secretions at time of ejaculation)

Question 15

what is Kallman syndrome (congenital - genetic cause of infertility)

Answer 15

• not enough sex hormone being made
• resulting in small testicles & reduced sperm counts

Question 16

what is Klinefelter syndrome (congenital - genetic cause of infertility)

Answer 16

• men have extra X chromosome -> XXY
• have azoospermia ie/ no sperm -> infertile

Question 17

explain degree of infertility for congenital genetic cause of infertility - Y chromosome microdeletions & Robertsonian translocation

Answer 17

• depending on where microdeletion is on Y chromosome -> determine severity of their infertility
• depending on where translocation occurring -> determine severity of their infertility
  -> generally ranges from mild to moderate sperm defects

Question 18

describe Androgen Insensitivity Syndrome (ie/ intersex)

Answer 18

• baby born genetically as male
• XY
• but present at birth with external female genitalia
• their testes located in position of where ovaries are

Question 19

what are some idiopathic factors (environmental, lifestyle) that contributing to reduced male fertility and poor reproductive health

Answer 19

• obesity
• alcohol consumption
• recreational drug use
• poor diet
• endocrine disruptors
• radiation
• heat exposure
• physiological stress
• environmental pollutants
• industrial chemicals

Question 20

can idiopathic environmental and lifestyle factors lead to modification of testes themselves & what does this lead to

Answer 20

• yes
• lead to changes in quality of sperm produced by testes

Question 21

when we say lead to reduced sperm quality what is this resulting in (idiopathic factors??)

Answer 21

• reduced sperm counts
• reduced motility
• reduced morphology
• sperm viability
• reduced inability to respond to oxidative stress (low antioxidants)

Question 22

for idiopathic factors, in most cases how can things return to normal

Answer 22

• when male removes themselves from factor they been exposed to eg/ lose weight, no tobacco

Question 23

these lifestyle and environmental factors are not only influencing male reproductive potential (fertility) they are also influencing….

Answer 23

• male reproductive health more broadly
• not only seeing decline in sperm counts
• also seeing increase in instance of other reproductive disorders (eg/ testicular cancer, undescended testes, hypospadias - urethral orifice not located at penis tip, earlier onset puberty age)

Question 24

there must be exposures to humans in last 50 years thats affecting infertility as well as reproductive health more broadly. true or false

Answer 24

true