Genetics

Question 1

Fragile X Syndrome

Answer 1

Genetic Defect: CGG trinucleotide repeat expansion on X-chromosome.
Clinical Presentation: Intellectual disability, developmental delay, elongated facial features, protruding jaw, and enlarged testes

Question 2

Autosomal Recessive trinucleotide repeat (GAA) on chromosome 9 the encodes for Frataxin

Answer 2

Friedreich Ataxia

Question 3

Clinical Presentation:
Muscle weakness and loss of DTRs, vibratory sense, proprioception. Staggering gait, frequent falling, nystagmus, dysarthria, pes cavus, hammer toes, diabetes mellitus, hypertrophic cardiomyopathy

Answer 3

Friedreich Ataxia

Question 4

Autosomal Recessive.
Mutation in the ATM gene on chromosome 11 = Impaired DNA repair.

Answer 4

Ataxia-Telangiectasia

Question 5

Neuropathy, Ataxia
Extraocular movement abnormalities: Inability to move the eyes without head thrusting.
High serum alpha-fetoprotein

Answer 5

Ataxia Telangiectasia

Question 6

X-linked Ataxia
CGG repeat in the FMR1 gene on Chromosome X.
Tremor, Ataxia, Parkinsonism, Dysautonomia, Cognitive decline, Family Hx of mental retardation.
MRI Brain: Hyperintensities in the cerebellum, Inferior Cerebellar peduncle

Answer 6

Fragile X Tremor-Ataxia Syndrome

Question 7

Autosomal Recessive
Defect in the enzyme 27-sterol hydroxylase on chromosome 2 = Deposition of cholesterol and cholestanol in tissues.
Presentation: Neuropsychiatric symptoms, Parkinsonism, Neuropathy, Tendon Xanthomas.
DX: Measurement of serum cholestanol
MRI: Cortical, Cerebellar atrophy, WM abnormalities
T/M: Chenodeoxycholic Acid

Answer 7

Cerebrotendinous Xanthomatosis

Question 8

Bilateral calcification of the basal ganglia and cerebellum

Answer 8

Striopallidodendate Calcinosis
Fahr’s Disease