Genetics

Question 1

Duchenne muscular dystrophy

Answer 1

X linked recessive
No male carriers, all affected
Appear in boys before age 6, muscle weakness/difficulty standing, life exp 25

25% chance affected son
25% chance carrier daughter
50% healthy woman

If fam hx, can have generics and consider ivf with PGD

Question 2

Translocations

Answer 2

If mother has it - 10% recurrence risk

If father has it - 2% risk

Question 3

Fragile X

Answer 3

1 in 1000 males
Responsible for 25% of male intellectual handicap
2nd only to tri 21

Prenatal testing available, nucleotide triplet repeat, expansion >220 repeats

Question 4

PKU

Answer 4

1 in 12 000
Autosomal recessive
Inborn error of metabolism - rise in phenylalanine, impaired myelination of brain and mental retardation