Question

The first child of normal parents is albinic then what would be the probability of their second child to be albinic again?
(Hint: Albinism is an autosomal recessive disorder)

Answer 1

Hint: Mendelian or gene-related human disorders are determined by mutations in single genes. These disorders follow Mendelian principles. Gene mutations in autosomes and gene mutations in sex chromosomes are the two types of Mendelian Disorders. An autosomal gene mutation can be divided into recessive and dominant genetic disorders. Albinism is an example of a recessive genetic disorder.

Complete step by step answer: Albinism is an autosomal recessive disorder, the parents of the child suffering must have one functional copy of the causative gene and one non-functional copy. They are referred to as carriers and do not show any signs or symptoms. Hence, there is a 50 per cent possibility that the second child will also suffer from albinism. The absence of the enzyme tyrosinase causes albinism. Melanin pigment synthesis takes place with the help of tyrosinase from dihydroxyphenylalanine. The enzyme tyrosinase is not produced by the gene for albinism. However, its normal allele produces tyrosinase. It explains the fact that this disease affects only homozygous recessive individuals. The symptoms of albinism include pale eye colour, pale skin and very light-coloured hair.
Oculocutaneous albinism (OCA) and ocular albinism (OA) are the two types of albinism.
The X-linked inheritance pattern is followed in ocular albinism. If the mutated gene is located on the X-chromosome, it is considered to be X-linked. Since males have one X chromosome and one Y chromosome, a single defect in the causative gene is enough to cause albinism. On the other hand, since females have two X chromosomes, women with one copy of the mutation usually do not experience any eye abnormalities or vision loss.

Note: Albinism is a genetic disorder that does not have any specific treatment. This disease affects only homozygous recessive individuals. Treatments usually include eye care and skin care. To date as many as seven forms of oculocutaneous albinism are now recognized; OCA1, OCA2, OCA3, OCA4, OCA5, OCA6 and OCA7.