Chapter 24, Problem 1IA

Summary Introduction

To determine:

The probability of the fourth child of Bob and Joan will be suffering from the autosomal recessive disorder, sickle cell anemia.

Introduction:

The autosomal genes are those genes, which are present on the non-sex chromosomes. Since, both the males and females have the autosomes, the probability of the diseased male and female is same. The recessive traits are those traits which are able to express only in the homozygous condition. These are not able to express in presence of the dominant allele. The sickle cell anemia is an example of the autosomal recessive disease.

Pictorial representation:

Given below is the cross showing the probable genotype of the child resulting from a cross between heterozygotes.

Fig.1:The cross between the heterozygous Bob and Joan.