In man,the genetic disorder 'Aniridia' (congenital absence of the iris) occurs due to:

In pedigree analysis,the symbol $ʘ$ is used for:

Infantile amaurotic idiocy $(Tay-Sachs disease)$ is

Identify the genetic disorders based on the following characteristics:
$(i)$ Presence of sickle-shaped $RBC$.
$(ii)$ Blood does not clot,leading to non-stop bleeding.
$(iii)$ The heterozygous female transmits the disease to sons.
$(iv)$ Both heterozygous parents transmit the disease to offspring.

In humans,a gene located on the $X$-chromosome can be responsible for:

If a colour blind lady marries a normal man,their children will be: