genetics

Question 1

Eight imprinting disorders

Answer 1

1) Prader willi syndrome
2) Angelman syndrome
3) Transient neonatal diabetes
4) Beckwith-Wiedemann syndrome
5) Russell-Silver syndrome
6) matUPD14
7) patUPD14
8) Pseudohypoparathyroidism 1B

Question 2

X-linked recessive disorder

Answer 2

1) Haemophilia A
2) G6PD deficiency
3) Chronic granulomatous disease
4) Fragile X syndrome
5) Color blindness
6) Duchenne and Becker muscular dystrophy
7) Testicular feminization
8) Fabry disease

Question 3

X-linked Dominant disorder:

Answer 3

1) Rett syndrome
2) Vitamin D resistant rickets
3) Incontinentia Pigmenti

Question 4

autosomal dominant

Answer 4

1) Neurofibromatosis type 1
2) Achondroplasia
3) Huntington disease
4) Hereditary Breast Ovarian Cancer Syndrome
5) Familial hypercholesterolaemia
6) Marfan’s

Question 5

autosomal recessive

Answer 5

1) Deafness
2) Albinism
3) Wilson disease
4) Sickle cell disease
5) Thallasemia
6) Cystic fibrosis
7) Homocystinuria
8) Friedreich’s ataxia
9) Phenylketonuria
10) Hemochromatosis
11) Alpha-1 antitrypsin deficiency

Question 6

nonsense mutation

Answer 6

point mutation in a sequence of DNA –>

• premature stop codon,
• truncated, incomplete, and usually nonfunctional protein product

Question 7

trinucleotide repeats

Answer 7

1) Friedreich’s ataxia (GAA)
2) Fragile X syndrome (CGG)
3) Huntington’s disease (CAG)
4) Myotonic dystrophy (CTG)

Question 8

mitochondrial disorders

Answer 8

1) MELAS - Mitochondrial Encephalomyopathy with Lactic Acidosis and Stroke Like episodes
2) MERRF - Myoclonic Epilepsy with Ragged Red Fibres
3) LHON - Leber Hereditary Optic Neuropathy
4) Kearn-Sayre syndrome (External opthalmoplegia)
5) NARP (Neurogenic weakness Ataxia with Retinitis Pigmentosa)

Question 9

Why do women sometimes manifest X-linked condition?

Answer 9

1) Skewed X inactivation (lyonisation)
2) Turner’s syndrome
3) Homozygous for mutation (rare)
4) May be X linked dominant or lethal in males.
5) X autosome balanced translocation

Question 10

Marfans clinical dx

Answer 10

Ghent nosology
-aortic root aneurysm and ectopia lentis are the cardinal clinical features. In the absence of any family history, the presence of these two manifestations is sufficient for the unequivocal diagnosis of Marfan Syndrome.