Question

Increased risk of what disease is associated with an older father?

a. Prader-willi syndrome

b. Angelman syndrome

c. hunter syndrome

d. noonan syndrome

Answer 1

d. Noonan syndrome.

Noonan syndrome is an pleomorphic autosomal dominant disease. Parents who have Noonan syndrome have 50% chance of passing mutation to children.

It is associated with increased paternal age.

Occur in approximately 1 in 1000-2500 . It affects both male and female equally.

They have close resemblance with female of Turner syndrome. Karyotype will show normal sex chromosome and normal karyotype(46XX or 46XY).

Clinical features: short stature, webbed neck, low set ears, cubitus valgus, micrognathia and hypertelorism, down slanting palpebral fissure, clinodactlyl, cryptorchidism, congenital heart diseases.

Prader willing syndrome: deletion of paternal genes after maternal gene silencing in 70% cases.

Uniparental disomy of maternal chromosome in 20-25%.

It can also be due to defective imprinting.

Here the child will be obese, poor muscle tone, underdeveloped genitals.

Angelman syndrome:Deletion of maternal genes after paternal gene silencing in 70% cases.

Uniparental disomy of parental chromosome in 20-25% cases.

It can also be due to defective imprinting.

Here the child will be with developmental delay. Also it will be happy, smilling child

Hunter syndrome:It is rare inherited genetic disorder due to deficiency of enzyme Iduronate 2 sulfatase

It is far more common in boys. It is mucopolysacharodosis 2..

Symptoms aren't present at birth but often begin arount age 2-4.It can be enlarged head, thickened lips, protruded tongue, hoarse voice, skeletal abnormalities.