A 36-year-old woman presents with secondary amenorrhea. Karyotyping shows 45,XO. What is the most likely diag… - NORCET 9 Prelims-2025

NORCET 9 Prelims-2025

Pathology & Genetics (E5)

Easy

Appeared in: NORCET 9 Prelims-2025

Explanation

Turner syndrome is a genetic condition resulting from the complete or partial absence of one X chromosome in females.
The 45,XO karyotype is the most common genetic signature for Turner syndrome, found in about half of the cases.
Ovarian dysgenesis (underdeveloped ovaries) is a hallmark of Turner syndrome, leading to premature ovarian failure. This causes a lack of hormone production, resulting in either primary amenorrhea (never starting a period) or secondary amenorrhea (periods stopping later in life), as seen in this 36-year-old patient.

Option B: Klinefelter syndrome is incorrect because it affects males and is characterized by a 47,XXY karyotype, meaning they have an extra X chromosome.
Option C: Androgen insensitivity syndrome is incorrect. Individuals with this condition are genetically male (46,XY) but their bodies are unable to respond to male hormones (androgens), leading to the development of female external characteristics. The karyotype does not match.
Option D: Asherman syndrome is incorrect because it is an acquired condition, not a genetic one. It involves the formation of scar tissue (adhesions) inside the uterus, usually after a procedure like a dilation and curettage (D&C). It would not cause an abnormal karyotype.

Visual 1: Karyotype Chart - A visual representation of a 45,XO karyotype, showing 22 pairs of autosomes and only a single X chromosome, to clearly illustrate the genetic abnormality.
Visual 2: Infographic - An infographic detailing the common physical features of Turner syndrome, such as short stature, webbed neck, low posterior hairline, and shield chest.
Visual 3: Diagram - A diagram comparing the developmental pathways in Turner syndrome vs. a normal female, highlighting the difference from streak ovaries to normal ovaries.

Clinical Relevance

Nursing practice connection: Use the key finding related to Diagnosis of genetic disorders based on karyotype and clinical presentation to guide bedside assessment, documentation, and the next nursing action.
Nurses must recognize that Turner syndrome requires lifelong, multidisciplinary care. This includes monitoring for associated conditions like heart defects (especially coarctation of the aorta), kidney problems, hearing loss, and autoimmune disorders (e.g., hypothyroidism).
Patient education is a key nursing role. This involves explaining hormone replacement therapy (estrogen and progestin) to induce puberty and maintain bone density, as well as discussing options for fertility, such as egg donation.
What if the patient's karyotype came back as 45,X/46,XX mosaic? The clinical presentation could be milder. Some women with mosaic Turner syndrome may have spontaneous puberty and even achieve pregnancy, although premature ovarian failure is still common. The management and monitoring principles would remain similar, but the prognosis for fertility might be slightly better.

How to Approach the Question

First, identify the core information in the question stem. The key findings are 'secondary amenorrhea' and the specific karyotype '45,XO'.
Recognize that a karyotype is a definitive genetic test. The result '45,XO' is the most crucial piece of data.
Systematically evaluate each option by comparing its known karyotype with the one provided in the question.
Option A (Turner syndrome) is known to be associated with 45,XO.
Option B (Klinefelter syndrome) is 47,XXY.
Option C (Androgen insensitivity syndrome) is 46,XY.

Concept Tested & Keywords

Concept Tested: Diagnosis of genetic disorders based on karyotype and clinical presentation.
Stem keywords: secondary amenorrhea, Karyotyping, 45,XO
Lead-in keywords: most likely diagnosis
Clinical cues: Patient is a 36-year-old woman, which is consistent with a diagnosis that can present with secondary amenorrhea in adulthood.
Clinical cues: Karyotype 45,XO is the definitive diagnostic finding.

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