Genetics

Question 1

Features of fragile X syndrome

Answer 1

Most common inherited intellectual disability. X chromosome w variable number of repeats. Long face, prominent ears, strabismus.

Question 1

What does genetic carrier screening involve?

Answer 1

Blood or saliva for Fragile X, spinal muscular atrophy and cystic fibrosis. Mother first, father if mother affected. Counselling is positive

Question 2

Features of prader willi syndrome

Answer 2

Chromosome 15 microdeletion, not inherited. Prenatal: SGA, reduced activity. Weakness, feeding problem, genital hypoplasia, developmental delay, GH deficiency - > hyperphagia, obesity later.

Question 3

What tests are used in hereditary haemochromatosis?

Answer 3

Elevated ferritin and transferrin sat. Check HFE if FDR or levels on 2 specimens. Homo C282Y - high risk, C282Y + H63D = compound hetero, 1% risk. Monitor iron 2-5 yearly, screen relatives. All others don’t increase risk, can be carrier.

Question 4

Symptoms of hereditary haemochromatosis. Differentials for elevated ferritin.

Answer 4

Bronze skin, diabetes, restrictive cardiomyopathy, cirrhosis, fatiugue, 2/3 MCP arthropathy, testicular atrophy. DDx: alcohol, metabolic syndrome, infection, hepatitis, NASH.

Question 5

How is huntington’s disease inherited? What are the features?

Answer 5

Autosomal dominant, 50% inherited. Chorea, abnormal behaviour, dementia. 20y fatality.