Karyotype of Klinefelter syndrome is?

Appeared in: PGIMER Sangrur NO - 2023

Explanation

Klinefelter syndrome is a genetic disorder where a male has an extra X chromosome.
The standard human male karyotype is 46,XY. The addition of an extra X chromosome results in the karyotype 47,XXY.
This is the most common sex chromosome abnormality in males, occurring in approximately 1 in 700 male infants.
The presence of the Y chromosome determines the male phenotype, but the extra X chromosome leads to features like hypogonadism, gynecomastia, and infertility.

Option B: The karyotype 47,YYY is not a recognized viable human syndrome. The X chromosome contains essential genetic information for survival, and its complete absence is lethal.
Option C: The karyotype 47,XXX corresponds to Triple X syndrome. Individuals are phenotypically female and often present with tall stature but typically have normal fertility.
Option D: The karyotype 47,XYY is associated with Jacobs syndrome. Individuals are phenotypically male, often tall, and have normal fertility, distinguishing them from those with Klinefelter syndrome.

Clinical Relevance

Nursing practice connection: Knowing Genetic basis of Klinefelter Syndrome helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses play a crucial role in educating patients and families about Klinefelter syndrome, including the need for lifelong testosterone replacement therapy starting around puberty to promote virilization and improve bone density.
Counseling regarding infertility is essential, as most men with 47,XXY are infertile due to azoospermia. Nurses can provide information on options like testicular sperm extraction (TESE) and IVF.
Patients with Klinefelter syndrome have an increased risk for certain health problems, including breast cancer, autoimmune disorders (like lupus and rheumatoid arthritis), and metabolic syndrome. Nurses should emphasize the importance of regular health screenings.

How to Approach the Question

This is a factual recall question that tests your knowledge of genetic syndromes.
First, identify the key term in the question: 'Klinefelter syndrome'.
Recall the definition of a karyotype, which is the number and appearance of chromosomes in the nucleus.
Access your memory of common sex chromosome abnormalities. Associate Klinefelter syndrome with a male phenotype having an extra X chromosome.
Evaluate the options: A normal male is 46,XY. An extra X chromosome would make the karyotype 47,XXY.
Eliminate the other options by recalling what they represent: 47,XXX is Triple X female, 47,XYY is Jacobs syndrome male, and 47,YYY is not viable.

Concept Tested & Keywords

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E6 Pathology-Vandana Puri & Kavita Gaur Textbook of Pathology and Genetics p. 569-571

E6 Obstetrics Williams p. 7-18

Practise the full PGIMER Sangrur NO - 2023

Attempt every question from this paper in a timed mock, then review the full solution for each one.