An extra chromosome, underdeveloped sex characteristics at puberty and a tendency to develop gynecomastia in… - PGICH Noida NO-2025

PGICH Noida NO-2025

Pathology & Genetics

Easy

Appeared in: PGICH Noida NO-2025

Explanation

Klinefelter syndrome is a genetic condition in males caused by the presence of an extra X chromosome, leading to a 47,XXY karyotype.
The extra X chromosome results in primary hypogonadism (testicular failure), which causes decreased testosterone production.
Low testosterone and a relative excess of estrogen lead to the classic signs of underdeveloped secondary sexual characteristics (e.g., reduced body hair, small testes) and gynecomastia (breast development).
Affected individuals are often taller than average with disproportionately long legs and arms, a feature also linked to the extra X chromosome.

Option A: Trisomy 18, or Edwards syndrome, is caused by an extra copy of chromosome 18, an autosome. It is not a sex chromosome abnormality and presents with severe, multi-system birth defects like heart problems, clenched fists, and rocker-bottom feet, which are not described in the question.
Option C: Fragile X syndrome is caused by a gene mutation on the X chromosome, not an extra chromosome. While it affects males, a key feature is macroorchidism (abnormally large testes), which is the opposite of the underdeveloped testes seen in Klinefelter syndrome.
Option D: Turner syndrome affects individuals who are phenotypically female and is caused by a missing X chromosome (45,X0). The features include short stature, a webbed neck, and ovarian failure. The question specifies a male patient.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Clinical manifestations of sex chromosome aneuploidies as background academic context rather than a clinical decision trigger.
Nurses play a crucial role in identifying signs of Klinefelter syndrome, which is often underdiagnosed until adulthood. Recognizing features like tall stature, gynecomastia, and small testes during adolescent health screenings can prompt referral for diagnosis.
Management involves testosterone replacement therapy, which nurses may administer and monitor. Patient education is vital regarding fertility options (e.g., testicular sperm extraction), and monitoring for associated health risks like breast cancer, osteoporosis, and autoimmune diseases.
What if? If the question described a male with similar features but also significant intellectual disability and more severe dysmorphism, a more complex aneuploidy like 48,XXXY or 49,XXXXY (variants of Klinefelter syndrome) might be considered, as the severity of features often increases with the number of extra X chromosomes.

How to Approach the Question

First, break down the clinical picture presented in the stem: 1) Male patient, 2) Has an extra chromosome, 3) Shows underdeveloped sex characteristics at puberty, and 4) Has gynecomastia.
The combination of 'male' and 'extra chromosome' affecting 'sex characteristics' strongly points to a sex chromosome aneuploidy.
Evaluate each option against these criteria:
Trisomy 18: This is an autosomal (not sex chromosome) trisomy with a different set of severe symptoms. Eliminate this option.
Klinefelter syndrome: This is defined by an extra X chromosome in males (47,XXY) and perfectly matches all the listed features: hypogonadism (underdeveloped characteristics) and gynecomastia. This is a strong candidate.
Fragile X syndrome: This is a gene mutation, not an extra chromosome, and causes enlarged testes, which contradicts the 'underdeveloped' description. Eliminate this option.

Concept Tested & Keywords

Concept Tested: Clinical manifestations of sex chromosome aneuploidies.
Stem keywords: extra chromosome, underdeveloped sex characteristics, gynecomastia, male
Lead-in keywords: features of
Clinical cues: Age/sex group narrows the expected diagnosis, intervention, or normal reference range.
Negative lead-in flag: false

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