Autosomal Inheritance

Human somatic (diploid, 2n) cells carry 23 pairs of chromosomes in total. Functionally these split into one pair of sex chromosomes, which determine sex, and the remaining 22 pairs, called autosomes, which govern the vast majority of an organism's other traits. The transmission of these non-sex-linked body characters from parents to offspring through the autosomes is called autosomal inheritance, and — unlike sex-linked traits — autosomal traits appear in males and females with equal frequency, and can appear to skip generations depending on dominance patterns.

Some characters are influenced by dominant genes and some by recessive genes present on the autosomes. For example:

• Autosomal dominant traits like widow's peak and Huntington's disease.
• Autosomal recessive traits like phenylketonuria (PKU), cystic fibrosis and sickle-cell anaemia.

a. Widow's peak : Widow's peak, a prominent V-shaped hairline on the forehead, is an example of an autosomal dominant trait: it appears in both homozygous dominant (WW) and heterozygous (Ww) individuals, while only the homozygous recessive genotype (ww) gives the alternative straight hairline; both sexes are equally likely to inherit either form.

…