Genetic Disorders

Question 1

___ is the proportion of those who inherit the gene and express its phenotype

Answer 1

penetrance

Question 2

____ is the variability in phenotypic expression among those who inherit the gene

Answer 2

expressivity

Question 3

[AD]

Tall stature, bilateral ectopia lentis, mitral valve prolapse, aortic aneurysm, hyperextensible joints

Answer 3

Marfan Syndrome

Fibrillin-1

Question 4

[AD]
corneal rupture, retinal detachment, rupture of colon and large arteries, diaphragmatic hernia, hyperextensible skin, hypermobile joints

Answer 4

Ehler-danlos syndrome

Fibrillar collagen defect

Question 5

____ disorders are noted to have complete penetrance and early onset and usually, enzyme defects

Answer 5

autosomal recessive disorders

Question 6

[AR]
Neurons are ballooned with cytoplasmic vacuoles with gangliosides (+) for oil red O, sudan black B, onion-skin configuration, (+) MR

Retina: (+) cherry-red spot, distended ganglion cells

NO Hepatosplenomegaly

Answer 6

Tay-Sachs disease

defect in hexominidase A leading to accumulation of GM2

Question 7

[AR]
cherry red spot in macula, hepatosplenomegaly, membranois inclusion of lamellated figures

(+) foam cells

Answer 7

Nieman-Pick Disease (Type A and B)

Sphingomyelinase deficiency

Question 8

[AR]
MR, erosion of long bones, hepatosplenomegaly,

crumpled tissue paper apperance (fibrillary cytoplasm), distended phagocytic cells in spleen, liver, BM, LN, tonsils, thymus, peyer patches

Answer 8

Gaucher disease

• most common,
• glucocerebrosidase deficiency (beta-glucosidase)

Question 9

All daughters are carriers, father doesnt transmit the disease to their sons, females may express the phenotype due to random inactivation of one chromosome

Answer 9

X-linked recessive disorder

Question 10

Give 2 examples of x-linked dominant disorders

Answer 10

Alport Syndrome, Vitamin D resistant rickets

Question 11

Failure of homologous chromosomes to separate during cell division

Answer 11

non-disjunction

Question 12

Trisomy 21 and Turner Syndrome are examples of post-fertilization error which is called

Answer 12

Mosaicism

Question 13

Most commonly associated cardiac anomaly in Trisomy 21

Answer 13

Endocardial cushion defect

Question 14

Trisomy 21 is most commonly associated with what type of leukemia

Answer 14

AML

Question 15

Prominent occiput, micrognathia, low set ears, short neck, overlapping fingers, congenital heart defect, renal malformations, limited hip abduction, rocker bottom feet

Answer 15

Trisomy 18: Edwards

Question 16

Microcephaly, micropthalmia, polydactyl, cleft lip and palate, cardiac defects, umbilical hernia, renal defect, rocker bottom feet

Answer 16

Trisomy 13: Patau

Question 17

Cardiac anomaly, abnormal facies, thymic hypoplasia, cleft palate, hypocalcemia, high risk for schizophrenia and bipolar disorder

Answer 17

Di George Syndrome: 22q11.2 deletion

Question 18

Eunochoid body habitus, testicular atrophy, micropenis, absent secondary sex characteristics, MVP, gynecomastia, T2Dm, metabolic synrome

Answer 18

Klinefelter: 47 XXY

Calvin Klein’s exes

Question 19

Short stature, no neck, cystic hygromas of the neck, preductal CoA, bicuspid aortic valve

Answer 19

Turner 45XO

Tina Turner is 45

Question 20

Genotypically male, phenotypically female

Answer 20

Androgen Insensitivity Syndrome

Question 21

MR, Long face, large mandible, large everted ears, macro-orchidism, CGG expansion in FMR1 gene

Answer 21

Fragile X, mutations may cause loss of function

Question 22

progressive movement disorders, dementia due to degeneration of striatal neurons

CAG expansion of Ch 4

Answer 22

Huntington Disease

Question 23

deletion in Paternally derived chromosome 15

Answer 23

Prader-Willi Syndrome

Question 24

deletion in maternally derived chromosome 15

Answer 24

Angelman Syndrome