Question

What do you mean by Mendelian disorders? Give two examples of sex-linked Mendelian disorder.

Hint:

Mendelian disorders trace back to a single gene; think of two X-linked recessive conditions.

Answer 1

Step 1: Understanding the Concept:
Mendelian disorders are disorders caused by an alteration (mutation) in a single gene, and they are passed from parents to offspring following the same inheritance patterns that Mendel described for pea plants: dominant, recessive, autosomal, or sex-linked.

Step 2: State the general idea.
Because only one gene is involved, the pattern of inheritance of a Mendelian disorder in a family can usually be traced using a pedigree analysis, and the disorder can be dominant or recessive, and located on an autosome or a sex chromosome.

Step 3: Give sex-linked examples.
Haemophilia is a sex-linked recessive disorder in which blood fails to clot normally, caused by a gene carried on the X chromosome.
Colour blindness is another sex-linked recessive disorder, in which a person cannot distinguish between red and green colours, also caused by a gene on the X chromosome.

Final Answer:
Mendelian disorders are single-gene disorders inherited in Mendelian fashion; haemophilia and colour blindness are two sex-linked examples.