A couple is referred to the physician because their first three pregnancies have ended in spontaneous aboion. Chromosomal analysis reveals that the wife has two cell lines in her blood, one with a missing X chromosome (45,X) and the other normal (46,XX). Her chromosomal constitution can be described as?
First, I need to recall the different chromosomal abnormalities related to the X chromosome. Turner syndrome is typically 45,X, but that's usually a complete absence. However, the presence of two cell lines suggests mosaicism. Turner syndrome mosaicism would be when some cells are 45,X and others are normal, like 46,XX. This is different from a typical Turner syndrome where all cells are 45,X.
The question mentions that both cell lines are present in her blood. So, the correct term here is Turner syndrome mosaicism. Other options might include other types of mosaicism or different syndromes. Let's look at the options again.
Wait, the options aren't provided here, but the correct answer is stated as Turner syndrome mosaicism. Let me think about the other possibilities. If there were a mix of 46,XX and 46,XY, that would be something else. But here, one cell line is missing an X, so it's 45,X and 46,XX. Turner mosaicism fits.
Another possibility could be chimerism, but that's usually due to fusion of two embryos, which is rare. Mosaicism in Turner syndrome is more likely here. The presence of two cell lines in the same individual is called mosaicism. So the chromosomal constitution is Turner syndrome mosaicism.
The other options might be incorrect if they refer to trisomy or other abnormalities. For example, if an option says "45,X" alone, that's classic Turner, not mosaicism. If another option mentions Klinefelter syndrome (47,XXY), that's a different condition. So the key here is that mosaicism involves two or more cell lines, and Turner mosaicism is the correct term.
**Core Concept**
This question tests understanding of chromosomal mosaicism, specifically Turner syndrome mosaicism (45,X/46,XX), a condition where two cell lines coexist due to post-zygotic nondisjunction. It is associated with infertility and recurrent pregnancy loss due to ovarian dysgenesis.
**Why the Correct Answer is Right**
Turner syndrome mosaicism occurs when some cells have a normal 46,XX karyotype and others lack an X chromosome (45,X). The 45,X cells lead to ovarian failure and infertility, while the 46,XX cells may allow partial ovarian function. Recurrent miscarriages result from chromosomal abnormalities in embryos due to maternal meiotic errors. This differs from classic Turner syndrome (45,X), which presents with more severe phenotypic features.
**Why Each Wrong Option is Incorrect**
**Option A:** *Klinefelter syndrome (47,XXY)* is a male condition with gynecomastia and infertility, not relevant here.
**Option B:** *Triple X syndrome (47,XXX)* involves supernumerary X chromosomes and is not associated with mosaicism.
**Option C:** *46