In an Autosomal Recessive (AR) disorder, one parent is normal and the other is carrier and the child is also affected. What is the reason: (A) Germ line mosaicism, (B) Genomic imprinting, (C) Penetration, (D) Uniparental disomy
Answer is D. Uniparental disomy refers to the situation in which 2 copies of a chromosome come from the same parent, instead of 1 copy coming from the mother, and 1 copy coming from the father. Angelman syndrome (AS) and Prader-Willi syndrome (PWS) are examples of disorders that can be caused by uniparental disomy. Reference: GHAI Essential pediatrics, 8th edition