genetics

Question 1

Downs syndrome usually occurs due to

Answer 1

nondisjunction in Meiosis in the Ovum
(can also occur due to robertsonian translocation)
-advanced maternal age is a risk factor

Question 2

pts with down’s syndrome at risk for which cancers

Answer 2

AML ALL

Question 3

acetylation of histones

Answer 3

enhances gene transcription

Question 4

deacetylation of histones

Answer 4

silences the genes

-in HD, the mt huntington gene enhances the deacetylation of genes

Question 5

hypermethylation of a transcription gene

Answer 5

leads to gene silencing

Question 6

neonate with lymphemeda and cystic hygromas

Answer 6

tuners syndrome

Question 7

t (15,17)

Answer 7

acute promyelocytic leukemia
-PML/RARalpha
M3 varian of AML
-younger pts, on smear see many auer rods, in

Question 8

t(8,14)

Answer 8

Burkitts lymphoma

-c-myc translocated to immunoglobin gnee

Question 9

t (9,22)

Answer 9

philadelphia chromosome, CML, bcr-abl

Question 10

t (11, 14)

Answer 10

mantle cell B lymphoma

-activation of cyclin D gene

Question 11

situs inversus + recurrent sinopulmonary infections

Answer 11

kartagener syndrome (immotile cilia syndrome)
-due to failure of dyenin arms to develop normally
-causes decreased clearing of epithelial cells
leads to infertility in men and can lead to infertility in women as well due to decreased fallopian tube cilia mobility
-autosomal recessive

Question 12

neonate with low-set ears, clenched fists, overlapping fingers, micrognathia, microcephaly, arnold chiari, rocker bottom feet, HYPERtonia, VSD, PDA, Meckels, malrotation

Answer 12

Edwards, trisomy 18

-key abnormal hand (clenched with overlapping fingers)

Question 13

cleft lip/palate, micropthalmia, coloboma, cyclops, deafness, scalp defects, PDA

Answer 13

Patau, trisomy 12

-most die within week and others rarely survive past 6 months,

Question 14

ataxia, cardiomyopathy, pes cavus, hammer toes, kyphoscoliosis,

Answer 14

Friedrich ataxia
-chromosome 9, increaased trinucleotide repeats
-10% also develop Diabetes mellitus
death usually by cardiomyopathy and/or bulbar dysfunction

Question 15

multiple telangiectasia of skin and mucosa with recurrent epistaxis

Answer 15

hereditary hemorrhagic telangiectasia (Osler-Rendu-Weber syndrome)

Question 16

FGFR 3 mutation

Answer 16

achondroplasia (dwarfism)
autosomal dominant, lethan in homozygous dominant
-therfore heterozygous person has 50% chance of having a short kid

Question 17

ectopia lensis, MR, vascular thromboses, marfanoid, osteoporosis

Answer 17

homocystinuria,
cystathionine beta synthase deficiency
an example of pleiotrophy

Question 18

increased AFP

increased Ach

Answer 18

Neural tube defects

Question 19

hypotonia, poor feeding, macroglossia, jaundice, constipation, hoarse cry

Answer 19

congenital hypothyroidism
prevents normal brain devleopment and myelination during early life
-also at higher risk of congenital heart risk (ASD/VSD)
-irreversible mental retardation,
-a normal screening test

Question 20

chromosome 22 long arm deletion

Answer 20

DiGeorge
CATCH 22
Cleft lip/cardiac anomalies like interrupted aortic arch
Abnormal facies
Thymic hypoplasia-recurrent viral infection due to decreased T cell maturation
Hypocalcemia due to pit abnormalities

Question 21

t (14,18)

Answer 21

follicular lymphoma (a non-Hodgkin lymphoma)
leading to overexpression of bcl-2–> a proto-oncogene tha tprevents the release of pro-apoptotic factors)
14-immunoglobin heavy chain enhancer

Question 22

histone located outside of nucleosome core

Answer 22

Histone H1, aid in DNA packing of regions between each core making entire structure more tight
inside (H2A, H2B, H3, H4)X2

Question 23

genetics of Alzheimer’s

Answer 23

ApoE4 associated with familial late onset AD

Presenilin 1 on chr 14, presenilin 2 on chr 1, and amyloid precursor protein on 21 associated with early onset AD

Question 24

polygenic conditions

Answer 24

• androgenetic alopecia
• epilepsy
• schizophrenia
• glaucoma
• ischemic heart disease
• hypertension
• TIID
• malignancy