Pediatrics - Congential and Biochemical Disorders

Question 1

Typical signs/symptoms of Down syndrome include the following, except for one:

A) brachycephaly

B) epicanthus

C) big tongue

D) cleft palate

E) muscle hypotonia

Answer 1

D) cleft palate

EXPLANATION
The major developmental disorders seen in the physical examination are rare in Down’s syndrome; most of the anomalies that can be seen are part of a group of minor anomalies (informative morphogenetic variants), some of which generate a distinctive appearance.

Question 2

The risk of a 41-year-old woman to give birth to a child with Down syndrome is:

A) 1: 100

B) 1: 350

C) 1: 800

D) 1: 1200

E) 1: 1850

Answer 2

A) 1: 100

EXPLANATION
According to statistics, the risk to develop Down syndrome increases in mothers over the age of 40, which justifies prenatal screening over 35 years.

Question 3

Regarding the prognosis of Down syndrome, the following statements are true, except:

A) if there is no serious developmental defect, the lifetime is equal with the average population

B) IQ level is various, but rarely higher than 60

C) women are fertile

D) men are sterile

E) the final height is below 10th percentile of the average population

Answer 3

A) if there is no serious developmental defect, the lifetime is equal with the average population

EXPLANATION
The average age is shorter in the absence of a serious developmental disorder as the connective tissue and vascular system of Down’s syndrome is “aging” faster than average.

Question 4

What is the correct number of the human haploid chromosomes?

A) 22

B) 23

C) 44

D) 46

E) 69

Answer 4

B) 23

EXPLANATION
Haploid refers to the single presence of the chromosome set. There are haploid sets in the gametes. This is the duplicate set in somatic cells in humans, that is, half of the 46 chromosomes, which is 23.

Question 5

These features are characteristic for Edwards syndrome, except for one:

A) severe intrauterine dysmaturity (growth retardation)

B) they are mostly immature and the gestational age is below under 30 weeks

C) finger III is covered by finger II, finger IV is covered by finger V

D) congenital anomaly of the heart

E) only a few survive the 2nd year of life

Answer 5

B) they are mostly immature and the gestational age is below under 30 weeks

EXPLANATION
Edwards syndromic newborns are mature, including a gestational age at 40-41 weeks. In comparison, their birth weight is between 1800 and 2000 g and it is a very pronounced intrauterine growth failure.

Question 6

Children nullsuffering from the following chromosomal abnormalities are not nulllikely to survive, except for one

A) autosomal monosomy

B) X monosomy

C) 21-monosomy

D) triploidy

E) 13-trisomy

Answer 6

B) X monosomy

EXPLANATION
Numeral autosomal abnormalities, with the exception of 21-trisomy, are virtually always non-viable. In contrast, numerical faults in sex chromosomes do not affect or hardly affect life expectancy. Thus, X-monosomy (Ullrich-Turner syndrome) is usually characterized by normal life expectancy. Exceptions to the cases involve vitium.

Question 7

What is foetopathy?

A) foetal harm after 13. weeks of gestation

B) foetal harm between 2-13. weeks of gestation

C) it is the consequence of the failure of first cell divisions after fertilization

D) chromosome-related illness of the foetus

Answer 7

A) foetal harm after 13. weeks of gestation

EXPLANATION
In intrauterine life, morphogenesis is divided into three major phases: - blastogenesis (from fertilization to 2nd pregnancy week); - organogenesis (embryonal age, organ formation and differentiation in gestational week 2-13); - phenogenesis (fetal age, further fine differentiation and growth, from the 13th week of pregnancy). Embryopathy occurs between week 2-13, while foetopathy occurs after the 13th week of pregnancy.

Question 8

What would you nullrecommend a healthy second degree cousin couple who want to get married?

A) do not undertake nullpregnancy due to nullhigh genetic risk

B) childbirth can only be undertaken under regular 3-week ultrasound follow-up during pregnancy

C) there is nullhigh risk of foetal chromosome aberration, so chorionic villi sampling is recommended

D) the risk slightly exceeds the average, pregnancy can be nullrecommended

Answer 8

D) the risk slightly exceeds the average, pregnancy can be nullrecommended

EXPLANATION
The proportion of common genes in brothers and sisters and in successive generations is halved. Therefore, in second-degree cousins it is only 1/32, and in their descendants it will be only 1/64. This only slightly increases the risk of recessive and polygenic disorders compared to non-blood relatives.

Question 9

What is not typical of homocystinuria?

A) it is the most common inherited form of amino acid metabolism disorder

B) disturbance of sulphur-containing amino acids

C) patients are mentally retarded

D) luxation of lens can be detected

E) body height exceeds the average

Answer 9

A) it is the most common inherited form of amino acid metabolism disorder

EXPLANATION
Homocystinuria is a characteristic sign, comparable to the Marfan syndrome in many respects, but it is very rare. The neonatal birth rate of the classical form based on cystation synthase deficiency is estimated at 1: 200,000.

Question 10

What is the prevalence of phenylketonuria?

A) 1: 1500

B) 1: 10 000

C) 1: 25 000

D) 1: 70 000

Answer 10

B) 1: 10 000

EXPLANATION
There are minor geographical and ethnic differences in the incidence of phenylketonuria, but in most countries, including Hungary, there is an incidence of 1: 8000 to 1: 10000.

Question 11

What kind of disorder reminds galactosaemia manifesting in the neonatal age?

A) sepsis

B) idiopathic respiratory distress syndrome

C) meconium ileus

D) congenital hypothyroidism

Answer 11

A) sepsis

EXPLANATION
Galactosemia is rarely manifested in neonates, but if this is the case, a clinical picture corresponding to direct hyperbilirubinaemia, hematoma, hepatomegaly, hepatic impairment, hematoma, hypoglycaemia and seizures results in sepsis. Therapy may be deceptive: suspended nutrition and glucose infusions as part of the treatment of sepsis may improve the condition in the debilitating state of the galactose (but the resumption of nutrition may, of course, be fatal).

Question 12

All of these disorders are detectable prenatally, except:

A) arginine-succinic acid disease

B) cystathionine beta synthase deficiency

C) Hunter-syndrome

D) Lesch–Nyhan-syndrome

E) Guillain–Barré-syndrome

Answer 12

E) Guillain–Barré-syndrome

EXPLANATION
Guillain-Barré syndrome is not inherited; it is an acquired illness with ascending paralysis, and is most often a virus infection.

Question 13

What is the inheritance of Duchenne muscular dystrophy?

A) X-linked recessive

B) X-linked dominant

C) autosomal recessive

D) autosomal dominant

E) not inherited, developed postnatally through an autoimmune manner

Answer 13

A) X-linked recessive

EXPLANATION
Duchenne’s disease is inherited by recessive sex (X-chromosome), so half of the children of the transmitting women will be sick. Transmission from father to son excludes this inheritance and diagnosis.

Question 14

Which enzyme defect is responsible for “classic” galactosaemia?

A) galactokinase

B) galactose-1-phosphate uridyltransferase

C) uridyl-diphosphate-galactose-4-epimerase

D) glucose-6-phosphatase

Answer 14

B) galactose-1-phosphate uridyltransferase

EXPLANATION
Galactose-1-phosphate uridyl transferase, in the absence of which galactose-1-phosphate cannot be converted to glucose-1-phosphate.

Question 15

Which disease is in the background if the neonatal presentation symptom is meconium ileus?

A) Hirschsprung’s disease

B) congenital hypothyroidism

C) enteritis necrotisans

D) cystic fibrosis (mucoviscidosis)

Answer 15

D) cystic fibrosis (mucoviscidosis)

EXPLANATION
In homozygous individuals in the CFTR (transmembrane regulator) gene, the “thickening” of the excretion of exocrine glands causes pulmonary and gastrointestinal symptoms. In the newborn, the latter may manifest in dense, sticky meconium, which the peristalsis of the infant cannot pass through the intestines, so ileus and perforation can be formed.

Question 16

During infancy an enlarged tongue is characteristic of the disorders listed below, except for one:

A) celiac disease

B) Down syndrome

C) Wiedemann–Beckwith syndrome

D) Hurler disease

E) hypothyroidism

Answer 16

A) celiac disease

EXPLANATION
There is no evidence of an enlarged tongue in celiac disease and visceromegaly is non-characteristic of the disease. Familial incidence of gliadine sensitivity is known, but inheritance is not yet clearly understood. The association of HLA haplotypes (HLA DQ2, HLADQ 8) is justified.

Question 17

Morphogenetic variants (minor anomalies) are the following, except for one:

A) multiple hair whorls

B) hypertelorism

C) mamilla accessoria

D) bifid uvula

E) caput succedaneum

Answer 17

E) caput succedaneum

EXPLANATION
Caput succedaneum is not congenital, but has a slight impairment during delivery. In sites exposed to pressure, this is a local oedema under the scalp, which does not have seams, and is not related to the morphogenesis.

Question 18

Congenital pyloric stenosis is characterised by one of the following:

A) It is often associated with other developmental abnormalities.

B) In mothers toxaemia of pregnancy is frequently present.

C) Autosomal recessive inheritance is present in the affected girls.

D) The prevalence is the same among boys and girls due to maternal smoking.

E) Boys are more frequently affected with multifactorial (polygenic) inheritance.

Answer 18

E) Boys are more frequently affected with multifactorial (polygenic) inheritance.

EXPLANATION
Pylorus stenosis in the boy: girl ratio is around 5: 1-6: 1. This also means that if a less susceptible daughter develops the disease, the risk of repetition is greater (“non-affected heredity”) in the succeeding brothers.

Question 19

How can we prevent the development of spina bifida/anencephaly?

A) The use of contraceptives must be halted to be finished at least half a year before prior to the planned conceiving.

B) At the time of conceiving you must be attentive in the care of optimal maternal folic acid intake.

C) During the first trimester, the mother should consume at least 250 mg of vitamin C daily.

D) The mother should follow a low cholesterol diet.

Answer 19

B) At the time of conceiving you must be attentive in the care of optimal maternal folic acid intake.

EXPLANATION
Providing adequate maternal folic acid is a good example of primary prevention. In addition to blocking occlusion errors, it may also play a role in reducing other developmental defects (liposuction, palate, cardiac defects).

Question 20

It is characteristic of inheritance of mitochondrial diseases:

A) the mother is the transmitter

B) only the father can be the transmitter

C) the mother and the father could transmit the disease, but mainly it manifests in girls

D) gender does not influence the inheritance

Answer 20

A) the mother is the transmitter

EXPLANATION
Only the mother can be the transporter, because in the oocyte of the gametes there are mitochondria, and in the sperm, virtually none. They lose their function during fertilization.

Question 21

Mutations of mitochondrial DNA can cause a disease mostly of the following organs, except for one:

A) Central nervous system

B) Muscles, connective tissue

C) Bone marrow

D) Liver

E) Heart and blood vessels

Answer 21

C) Bone marrow

EXPLANATION
Mutations of mitochondrial DNA generally exhibit a variety of manifestations. The organs of haematopoiesis are rarely or only secondarily affected.

Question 22

Characteristic for teratogenic effects:

A) The onset of the defect is immediately after the fertilization

B) The injury depends on both the type of effect and time of it

C) The consequences of the teratogenic effects are more severe in mothers older than 35 years

D) The same teratogenic effect may have variable manifestations in different ethnic groups

Answer 22

B) The injury depends on both the type of effect and time of it

EXPLANATION
The quality of the maleficence of the teratogen can be crucial: certain noxae and reagents, for example, are likely to have a specific effect on the differentiation of given organs. The time of the effect is also important: certain developmental disorders only develop in specific stages of the differentiation.

Question 23

A newborn is presented with intrauterine atrophy, difficulties in feeding, developmental delay, muscle hypotonia, short palpebral fissure, snub nose, hypoplastic maxilla and flat philtrum. These signs are suspicious for:

A) Mosaic Down syndrome

B) Phenylketonuria

C) Fetal alcohol syndrome

D) Fetal hydantoin syndrome

E) Congenital rubella syndrome

Answer 23

C) Fetal alcohol syndrome

EXPLANATION
The symptoms listed in the question are textbook examples of foetal alcohol syndrome. It needs to point out, however, in which the clinical picture is often poor, only several symptoms manifest, and given the nature of the syndrome, history taking can be deceptive, largely due to the involved mothers mostly deny alcohol consumption. Based on published literature, the development of foetal alcohol syndrome can be expected in the chronic consumption of the equivalent of 80g pure alcohol a day, with significant individual variation.

Question 24

One of the following viral infections during pregnancy can result in developmental malformation in the fetus:

A) Parotitis epidemic

B) Influenza A2

C) Hepatitis A

D) Hepatitis B

E) Varicella

Answer 24

E) Varicella

EXPLANATION
95-98% of mothers have an immunity to varicella due to their childhood contraction of the disease. If a pregnant mother contacts varicella, the gravidity may result in a spontaneous abortion, or, in some cases, foetal damage can develop: limb deformity, shortening of limbs, microcephaly, hydrocephaly, microphthalmy, cataract, chorioretinitis, extensive and deep scars on the skin’s surface. Since these rarely occur, most geneticists do not recommend termination. Varicella towards the end of the gravidity can lead to inflammatory disorders in the foetus, of which varicella pneumonia is the most severe.

Question 25

The most severe consequence of the intrauterine Listeria infection is:

A) microcephaly

B) purulent meningitis

C) pneumonia

D) peritonitis

E) myocarditis

Answer 25

B) purulent meningitis

EXPLANATION
Listeria monocytogenes infection in the mother rarely leads to developmental malformation, however, maleficence is a more severe problem, as it mostly leads to spontaneous miscarriage, stillbirth or a premature birth. In the latter case, severe sepsis can be observed in the neonate, and purulent meningitis is a clear sign. Cutan granulomatosis (granulomatosis infantis eptica) is also a characteristic of maleficence.

Question 26

Which chromosome aberration can induce Down syndrome?

1) Non-disjunction, otherwise known as clear trisomy
2) Balanced translocation
3) Mosaic trisomy
4) Point mutation

A) 1st, 2nd and 3rd answers are correct

B) 1st and 3rd answers are correct

C) 2nd and 4th answers are correct

D) only the 4th answer is correct

E) all of the answers are correct

Answer 26

B) 1st and 3rd answers are correct

EXPLANATION
21 trisomy is the cause of Down Syndrome. This can manifest, due to nondisjunction, as “pure” trisomy, translocation and mosaicism.

Question 27

There is a newborn with multiple congenital malformations. Which of the following statements are true?

1) It is necessary to exclude the intrauterine infection (TORCH) in the mother and newborn as well.

2) If the past medical history was negative during the pregnancy, the teratogenic effect could be excluded.

3) We need to set up the etiologic diagnosis even in the case of perinatal death.

4) If the malformations are too severe and there is no chance of survival, it is not recommended to burden the newborn with further examinations to find the diagnosis.

A) 1st, 2nd and 3rd answers are correct

B) 1st and 3rd answers are correct

C) 2nd and 4th answers are correct

D) only the 4th answer is correct

E) all of the answers are correct

Answer 27

B) 1st and 3rd answers are correct

EXPLANATION
One must attempt to clarify etiology, even if in at least half of the cases prove unsuccessful. The damaged foetus’s further treatment may depend on it, and most importantly, the valuation of the risk of recurrent disease in the next pregnancy. Investigating the character of the intrauterine infection (with culture and serology) is an urgent task, as the results cannot be interpreted later due to possible other, later contracted infections.

Question 28

Which infant metabolic disease could be treated by diet?

1) Galactosemia

2) Maple syrup urine disease (MSUD)

3) Homocystinuria

4) Lesch–Nyhan syndrome (LNS, juvenile gout)

A) 1st, 2nd and 3rd answers are correct

B) 1st and 3rd answers are correct

C) 2nd and 4th answers are correct

D) only the 4th answer is correct

E) all of the answers are correct

Answer 28

A) 1st, 2nd and 3rd answers are correct

EXPLANATION
Diet therapy is also indicated in numerous other metabolical disorders. The effectiveness differs, it is most effective in which only the metabolism of a given nutrient is affected (PKU, galactosaemia). Where the conversation of multiple molecules is inhibited, and only a protein-poor diet can be prescribed, for example, the effectiveness of the therapy is poorer. This is also true in Lesh-Nyhan disease, in which the meat and protein poor diet is intended to lower purine intake, and has only a moderate effect.

Question 29

The Turner syndrome could be recognized based on the following:

1) Low birth weight

2) Swollen hands and feet are seen at birth

3) Webbed neck

4) Low hairline at the back of the neck

A) 1st, 2nd and 3rd answers are correct

B) 1st and 3rd answers are correct

C) 2nd and 4th answers are correct

D) only the 4th answer is correct

E) all of the answers are correct

Answer 29

E) all of the answers are correct

EXPLANATION
The symptoms listed in the question are characteristic. Occasionally shorter Type IV metacarpals, thin, hyperconvex nails on the hand, and hypoplasias nails on the foot, and wide set mammillae appear in new-borns.

Question 30

The typical symptoms of Klinefelter syndrome:

1) tall body height
2) gynecomastia
3) delayed puberty
4) stenosis of the aorta

A) 1st, 2nd and 3rd answers are correct

B) 1st and 3rd answers are correct

C) 2nd and 4th answers are correct

D) only the 4th answer is correct

E) all of the answers are correct

Answer 30

A) 1st, 2nd and 3rd answers are correct

EXPLANATION
The tall stature in Klinefelter syndrome does not resemble Marfan syndrome, as the faults of the heart and large arteries are not unusually severe.

Question 31

The symptoms of the triple-X (47, XXX) syndrome can be:

1) unusually large breasts
2) early puberty
3) striae on the trunk and abdomen
4) female body type at the physical examination

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 31

D) only the 4th answer is correct

EXPLANATION
Young girls with triple-X-syndrome cannot be fully diagnosed by a physical examination. Inspection and palpation cannot reveal clear symptoms, even in adults. Strabismus, epicanthic folds, a pitting nasal bridge, hypertelorism, clinodactyly of the little fingers, a low level of kyphosis and scant pubic hair are all statistically more common, however, these also occur otherwise, and therefore, they are not characteristic signs, and are unremarkable individually.

Question 32

Indication for chromosome test can be:

1) severe mental retardation
2) uncertain gender of the newborn
3) multiple minor abnormalities
4) suspicion of an X linked inheritable disease

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 32

A) 1st, 2nd and 3rd answers are correct

EXPLANATION
A chromosome investigation is, naturally, also indicated in multiple significant developmental disorders, and in the combination of major and minor disorders, including the potential if and when family members present the indicated signs. A chromosome investigation is also indicated in the parents of children with chromosome disorders and in their healthy siblings to demonstrate balanced chromosome deviation, and in parents, particularly in case of repeated miscarriages and/or stillbirths.

Question 33

It’s worth to conduct a neonatal screening for a disease if it is:

1) extremely rare, and would not be suspected normally
2) asymptomatic in newborns, but later it causes irreversible damage
3) causes early mortality, therefore you have to prepare the parents
4) at early recognition, it can be treated effectively

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 33

C) 2nd and 4th answers are correct

EXPLANATION
A further provision in the screening and ruling out asymptomatic, yet potentially harmful, and treatable diseases, is for to be common in the given population, and for the screening method to be reliable, it should be harmless to the newborn, and should not be a monetary burden upon society

Question 34

Congenital malformations associated with polyhydramnios:

1) duodenal atresia
2) renal agenesis
3) esophageal atresia
4) pulmonary hypoplasia

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 34

B) 1st and 3rd answers are correct

EXPLANATION
Describing the amount of the amniotic fluid and its other characteristics (color, purity, smell), and, when the new-born is moved, communicating these to the neonatologist is of immense benefit in raising awareness to the possibility of certain congenital disorders or diseases. Duodenal atresia, which causes an abnormality in the absorption of the swallowed amniotic fluid, and oesophageal atresia, can both lead to polyhydramnios. Renal agenesia and pulmonary hypoplasia occur with oligohydramnios.

Question 35

The result of the chromosomal analysis made from chorion sample can be affected by:

1) blood in the sample
2) infection
3) limited mitosis
4) the mix of maternal cells

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 35

D) only the 4th answer is correct

EXPLANATION
Pseudomosaicity, the transfusion with maternal cells, is the primary risk when highlighting misdiagnosis. Other factors can influence the investigation, in which the investigation results are unsuccessful, and will have to be repeated, however, it does not lead to misdiagnosis.

Question 36

The three main groups of the genetically determined birth defects can be categorized as originating from monogenic, polygenic and chromosomal harm. Which ones of these statements can be true for the main characteristics?

1) the monogenic harm inherit under Mendel’s laws
2) family aggregation can occur in all three groups
3) chromosome disorders can cause multiple congenital malformations
4) monogenic harm can be excluded if, excluding the affected child, no one is ill

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 36

A) 1st, 2nd and 3rd answers are correct

EXPLANATION
The answers are self-explanatory. The 4th answer is false, as even in the case of a mendelian monogenic inheritance, generally speaking, only the index case has symptoms, such as, in the event of an autosomal recessive, sex-linked recessive inheritance (only female conductor gene carriers in the known lineage) and a new mutation.

Question 37

A way of inheritance that is divergent from the classic Mendel’s law can be defined with the notion below:

1) uniparental disomy
2) imprinting
3) triplet amplification
4) mitochondrial inheritance

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 37

E) all of the answers are correct

EXPLANATION
Uniparental dysomia: This refers to the case of two homogenous chromosomes, or chromosome sequences from the same parent, i.e., from the father or the mother, the corresponding chromosome sequence from the other parent is missing from the descendant cell.

Question 38

Typical symptoms of phenylketonuria are:

1) the newborn seems healthy at physical examination
2) eczema
3) thin, blond hair
4) neurological symptoms

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 38

E) all of the answers are correct

EXPLANATION
The listed symptoms of phenylketonuria occur in untreated children, or in poorly calibrated, or unkept diets. Based on retrospective statistical data, a mild hypopigmentation can occur, even in newborns, however, this has no diagnostic value

Question 39

What symptoms can make you consider storage disorders on the wide spectrum?

1) coarsening of facial features
2) thick, bushy hair and eyebrows
3) big tongue
4) hepatosplenomegaly

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 39

E) all of the answers are correct

EXPLANATION
In certain organs and body parts, the storage of unmetabolizable materials initiates intrauterine. This is especially apparent in the storage of certain big molecule materials (mucolipidoses, mucopolysaccharidosis). Coarse facial features, or the absence of visceromegaly, does not rule out the possibility of other, similar metabolic disorders!

Question 40

Which statements are correct for Fragile X syndrome, the most common background for congenital mental retardation?

1) Mental retardation is more frequent and severe in boys
2) The mutation is unstable, it can change during inheritance and also in the body
3) The disorder can develop through CGG triplet amplification
4) Appearance in the family doesn’t follow Mendel’s laws

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 40

E) all of the answers are correct

EXPLANATION
The classic syndrome in its non-Mendelic, varying form, which accounts for most of the cases, is caused by the CGG triplet-amplification (allele expansion) of the FMR1 gene (see question 3.59). It is characterized by an oblong face with salient forehead and jaws, thick lips, enlarged and projecting ears and enlarged testes. In one-third of the cases, autism, epilepsy, and during childhood, aggressiveness can occur. The disease derives its name from the fragility of the X chromosome on its q27.3 region. Rarely is the underlying cause associated with some other triplet amplification.

Question 41

Marfan syndrome is inherited in the autosomal dominant pathway. The inheritance of the disorder is monogenic but still affect more organs. Which concept can explain that?

1) mosaicism
2) the cause of the symptoms is the mutation of that one gene that affects the synthesis of the connective tissue called fibrillin
3) increased expressivity
4) pleiotropy

A) 1st, 2nd and 3rd answers are correct
B) 1st and 3rd answers are correct
C) 2nd and 4th answers are correct
D) only the 4th answer is correct
E) all of the answers are correct

Answer 41

C) 2nd and 4th answers are correct

EXPLANATION
Pleiotropy is a historic concept with regards to genetics. Pleiotropy refers to the mutation of a single gene and it can create seemingly unrelated deviations in several organs or systems. The reason in support of the concept has been clarified in a variety of cases known in contemporary research. For example, in Marfan’s Syndrome, the mutation causes an anomaly in the connective tissue through the gene of the fibrillin, which manifests in the eye, the vessels, the skin, the joints, etc. In this case, pleiotropy (and likely in general, as well) is, therefore, a secondarily diffuse effect, which manifests in several locations.