The pedigree chart given below shows a particular trait which is absent in parents but present in the next generation irrespective of sexes. Draw your conclusion on the basis of the pedigree.

The given pedigree represents an Autosomal recessive trait.Autosomal because the trait is expressed irrespective of sexes. Recessive because it is not expressed in parent generation (carriers of trait) but seen in their offspring’s.

For example Sickle –cell anaemia that can be transmitted from parents to offspring when both the parents are carrier of the gene. The disease is controlled by a pair of allele Hb^A and Hb^S. Out of the three possible genotypes only homozygous individuals for Hb^S (Hb^SHb^S) show the diseased phenotype. Heterozygous (Hb^AHb^S) individuals appear unaffected but are the carrier of the disease as there is 50% probability of transmission of mutant gene to progeny.