Question

Cystic fibrosis is a/an

• A. sex-linked recessive disorder
• B. autosomal dominant disorder
• C. autosomal recessive disorder
• D. sex-linked dominant disorder

Answer 1

Answer: (C)

Mendelian disorders are mainly determined by alteration or mutation in the single gene. These disorders are transmitted to the offspring on the same lines as we have studied in the principle of inheritance. The pattern of inheritance of such Mendelian disorders can be traced in a family by the pedigree analysis. Most common and prevalent Mendelian disorders are Haemophilia, Cystic fibrosis, Sickle-cell anaemia, Colour blindness, Phenylketonuria, Thalassemia, etc.
Cystic fibrosis, sickle-cell anaemia and phenylketonuria are examples of autosomal recessive disorders, while haemophilia and colour blindness are sex-linked disorders (both of them are X-linked recessive disorders). Examples of autosomal dominant includes myotonic dystrophy.