Genetic disorder may be grouped into two categories

$(i)$ Mendelian Disorders These genetic disorder are mainly caused by alternation and mutation in the single gene. They are transmitted to offsprings following the principle of inheritance. Mendelian disorder can be dominant or recessive. $e.g.,$ haemophilia, colour blindness, sicklecell anaemia, cystic fibrosis, phenylketonuria, thalassaemia.

$(ii)$ Chromosomal Disorders Chromosomal disorder are caused due to excess, absence, or abnormal arrangement of one or more chromosome, $e.g.,$ Turner's syndrome, Down's syndrome, etc