Which of the following is a Mendelian disorder in human beings?

Mendelian disorders result from a mutation of a single gene. The gene may be present on an autosome or on a sex chromosome. The trait (disorder) may be dominant or recessive. The most common and prevalent Mendelian disorders are haemophilia, cystic fibrosis, sickle cell anaemia, colour blindness, phenylketonuria, thalassemia, etc. Down’s syndrome, Turner’s syndrome, Klinefelter’s syndrome are chromosomal disorders.