Question

A hereditary disease which is never passed on from father to son is
A. Autosomal linked disease
B. X-chromosome linked disease
C. Y-chromosomal linked disease
D. None of the above

Answer 1

Hint:- Genetic disorders are mainly of two types — chromosomal disorders and Mendelian disorders. If The underlying cause for a disorder is a change in the number of chromosomes it will be regarded as a chromosomal disorder. But If the cause is a change in the structure, and function of a gene then the disorder will be Mendelian disorder. Further Mendelian disorders are classified as Autosomal and Sex-linked disorders (X-linked or Y-linked).

Complete step-by-step solution:- In Autosomal disorders, the abnormal gene is inherited from either of the parents into the offspring.
-An autosomal linked disease can be inherited from a father to his son.
-In the case of X-linked dominant disorder, if both the parents are normal, none of their
children will be diseased. But if only the mother is diseased some sons can be normal
and if only the father is deceased, none of the daughters can be normal.
-In the case of X-linked recessive disorder, if both the parents are diseased, none of their
children can be normal. But if the only mother is diseased, none of the sons can be
normal and if only the father has disease, none of the daughters will be diseased.
-The genes of some somatic characters are located on the Y-chromosome.
-The inheritance of such a type of character takes place only through males. Such types
of characters are called Holandric characters. These are found only in males.
-Holandric — father to son and from son to grandson (male to male inheritance).
-Thus the correct answer is option B.

Note:-
Autosomal and sex-linked disorders (Mendelian disorders) are mainly determined by alteration ormutation in the single gene. Chromosomal disorders on the other hand are caused due to the absence or excess or abnormal arrangement of one or more chromosomes.Examples of common chromosomal disorders include — Down Syndrome, Turner's Syndrome, and
Klinefelter's Syndrome.Examples of common Mendelian disorders include — Sickle Cell Anemia, Huntington's Chorea.