54. On basis of statement given below the mode of inheritance is
• Mostly males are sufferer of disease
• All male child of affected mother are diseased
• Female develop disease only when her father is diseased and mother is carrier
(1) X-linked recessive
(2) X-linked dominant
(3) Autosomal dominant
(4) Autosomal recessive
Introduction:
The mode of inheritance described in the question points to a classic X-linked recessive pattern. This pattern is characterized by mostly males being affected, all male children of an affected mother being diseased, and females only showing the disease when inheriting it from an affected father and carrier mother. Understanding these features helps distinguish X-linked recessive inheritance from other genetic inheritance types.
Explanation of the given inheritance and options:
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X-linked recessive:
This mode affects males predominantly, as males have only one X chromosome. If a male inherits the mutated X chromosome from his mother (who may be a carrier), he will express the disease. Females, having two X chromosomes, usually need mutations on both X chromosomes to be affected; otherwise, they become carriers. An affected mother passes the mutated gene to all her sons, who will all be affected, while daughters may be carriers. Females develop the disease only if they inherit the mutated gene from both an affected father and a carrier mother. The absence of male-to-male transmission and higher male affectedness are key features. -
X-linked dominant:
In X-linked dominant inheritance, both males and females can be affected, though females may show milder disease due to two X chromosomes. Affected males pass the disease to all daughters but not to sons. The key difference is that females can be directly affected even if only one mutated X chromosome is present, unlike recessive inheritance. Male to male transmission doesn’t occur here either. -
Autosomal dominant:
This inheritance pattern involves mutations on non-sex chromosomes. Both males and females are equally likely to be affected, and the disease often appears in every generation since only one copy of the mutated gene is needed. Affected individuals transmit the mutation to 50% of their offspring regardless of sex, which contrasts with the sex-linked pattern described. -
Autosomal recessive:
Both males and females are equally affected, as two copies of the mutated gene (one from each parent) are required for disease expression. The disease often skips generations because carriers (with only one mutated gene) do not show symptoms. Male predominance is not typical in this inheritance mode.
Summary Table:
| Mode of Inheritance | Affected Individuals | Affected Males | Female Disease Expression | Transmission Pattern |
|---|---|---|---|---|
| X-linked recessive | Mostly males; female carriers | Mostly yes | Only if father affected & mother carrier | No male-to-male; sons of carrier mothers affected |
| X-linked dominant | Both males and females | Yes | Females affected if one mutated X | No male-to-male; all daughters of affected males affected |
| Autosomal dominant | Both males and females equally | Yes | Females affected if one mutated gene | Male and female equally affected; vertical transmission |
| Autosomal recessive | Both males and females equally | Yes | Females affected when two mutated genes | Disease may skip generations; equal sex ratio |
This detailed explanation supports the conclusion that the inheritance pattern described is X-linked recessive, given the predominance of affected males, affected sons of carrier mothers, and females affected only if their father is diseased and mother is carrier.
SEO Optimized Final Answer:
The mode of inheritance described in the question is X-linked recessive. In this pattern, mostly males are affected, all sons of an affected mother inherit the disease, and females only show the disease when their father is affected and their mother is a carrier. This contrasts with X-linked dominant, autosomal dominant, and autosomal recessive inheritance, which show different sex ratios and transmission patterns. Understanding these distinctions is crucial in genetics and disease prediction.
Keywords used: X-linked recessive inheritance, affected males, carrier mother, genetic inheritance pattern, X-linked dominant, autosomal recessive.
