Q.
In humans, polydactyly (i.e, presence of extra fingers and toes) is determined by a dominant autosomal allele $(P)$ and the normal condition is determined by a recessive allele $(p)$. Find out the possible genotypes of family members $1$, $2$ and $3$ in the given pedigree.
$1$
$2$
$3$
(a)$\,\,$
$PP\,\,$
$Pp\,\,$
$pp\,\,$
(b)$\,\,$
$PP\,\,$
$PP\,\,$
$pp\,\,$
(c)$\,\,$
$Pp\,\,$
$PP\,\,$
$Pp\,\,$
(d)$\,\,$
$Pp\,\,$
$Pp\,\,$
$pp\,\,$
| $1$ | $2$ | $3$ | |
|---|---|---|---|
| (a)$\,\,$ | $PP\,\,$ | $Pp\,\,$ | $pp\,\,$ |
| (b)$\,\,$ | $PP\,\,$ | $PP\,\,$ | $pp\,\,$ | (c)$\,\,$ | $Pp\,\,$ | $PP\,\,$ | $Pp\,\,$ |
| (d)$\,\,$ | $Pp\,\,$ | $Pp\,\,$ | $pp\,\,$ |
Principles of Inheritance and Variation
Solution:
Given pedigree chart for polydactyly (autosomal dominant trait) can be explained as follows :
