If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is:
If a genetic disease is transferred from a phenotypically normal but carrier female to only some of the male progeny, the disease is:
The correct option is (C) Sex-linked recessive
Genetic disease
A genetic disease is caused by a change or mutation in a person’s DNA sequence. It is of different types as follows:
- Autosomal dominant disease
- Autosomal recessive disease
- Sex-linked dominant disease
- Sex-linked recessive disease
Carrier
An individual who carries mutant genes and is capable of passing thegenetic mutation to the next generation is called a carrier.
The female in question is phenotypically normal and hence, is the disease carrier.
Sex-linked recessive trait
If the genes on X chromosomes are responsible for a trait and show expression only in homozygous conditions, then such traits are X-linked recessive traits. In sex-linked recessive diseases, both copies of the gene should be mutated in the female to express the diseased phenotype. In this case, the disease is transmitted to 50% of the males from the mother carrier but not to the females of the next generation.
The female is phenotypically normal in the question, and some of her sons were diseased. Hence, one of the X chromosomes in the female is mutant, carrying the defective allele. Her male sons, who inherited the diseased allele, were affected due to hemizygous condition.
Final answer: (C) Sex-linked recessive
Related Questions
The correct option is (C) Sex-linked recessive
Genetic disease
A genetic disease is caused by a change or mutation in a person’s DNA sequence. It is of different types as follows:
- Autosomal dominant disease
- Autosomal recessive disease
- Sex-linked dominant disease
- Sex-linked recessive disease
Carrier
An individual who carries mutant genes and is capable of passing thegenetic mutation to the next generation is called a carrier.
The female in question is phenotypically normal and hence, is the disease carrier.
Sex-linked recessive trait
If the genes on X chromosomes are responsible for a trait and show expression only in homozygous conditions, then such traits are X-linked recessive traits. In sex-linked recessive diseases, both copies of the gene should be mutated in the female to express the diseased phenotype. In this case, the disease is transmitted to 50% of the males from the mother carrier but not to the females of the next generation.
The female is phenotypically normal in the question, and some of her sons were diseased. Hence, one of the X chromosomes in the female is mutant, carrying the defective allele. Her male sons, who inherited the diseased allele, were affected due to hemizygous condition.
Final answer: (C) Sex-linked recessive
