Anhidrotic dysplasia is a condition in which development of sweat glands is prevented. It is caused by
mutation present on the X chromosome. A heterozygous female for this allele will:
(1) Show complete absence of sweat glands.
(2) Have normal phenotype
(3) Show mosaic pattern of presence and absence of sweat glands
(4) Show increased physiological activity of sweat glands
🧬 What Is Anhidrotic Dysplasia?
Anhidrotic ectodermal dysplasia is a genetic disorder that affects the development of sweat glands, hair, and teeth. One of its hallmark features is the absence of sweat glands (anhidrosis), which can lead to problems with temperature regulation.
This condition is X-linked recessive, meaning that the gene responsible for the disorder is located on the X chromosome.
👩⚕️ Genetics Behind the Disorder
Males (XY) who inherit the mutated gene from their mother will express the disorder, as they have only one X chromosome.
However, females (XX) with one normal and one mutated copy of the gene are known as heterozygous carriers. Their expression of the condition is not uniform and often results in a mosaic phenotype.
🔬 Why Do Heterozygous Females Show a Mosaic Pattern?
This phenomenon is due to a biological process called X-chromosome inactivation (Lyonization). In early development, one X chromosome is randomly inactivated in each cell.
As a result:
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Some cells express the normal gene, leading to normal sweat gland development.
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Other cells express the mutant gene, resulting in absent sweat glands.
This creates a patchy (mosaic) distribution of functional and non-functional sweat glands across the skin.
✅ Correct Answer:
(3) Show mosaic pattern of presence and absence of sweat glands
🔍 Summary of the Answer:
A heterozygous female for an X-linked anhidrotic dysplasia mutation will not show complete absence of sweat glands. Instead, due to random X-inactivation, she exhibits a mosaic pattern where some skin regions have sweat glands and others do not.
🧠 Key Takeaways:
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Anhidrotic dysplasia is X-linked recessive.
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Heterozygous females display a mosaic pattern due to X-chromosome inactivation.
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The condition impacts sweat glands, hair, and teeth development.
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Genetic counseling is essential for carriers.
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Anhidrosis in heterozygous females