Which scenario would not typically prompt chromosomal analysis?

Which scenario would not typically prompt chromosomal analysis?

• A. A child with phenylketonuria (PKU)
• B. A child with multiple congenital anomalies and mental retardation
• C. A couple with a history of multiple miscarriages
• D. A man with large testes and mental retardation

Answer: (A)

Chromosomal analysis is used when there’s a suspicion of a chromosomal abnormality that could explain development, anatomy, or pregnancy outcomes. A metabolic condition like phenylketonuria is diagnosed with newborn screening and biochemical testing, not by looking at chromosomes, so it would not typically prompt chromosomal analysis. In contrast, a child with multiple congenital anomalies and intellectual disability often prompts cytogenetic testing to look for deletions, duplications, or other chromosomal changes. A couple with a history of miscarriages may reveal a balanced chromosomal rearrangement in one parent, which is a common reason for parental karyotyping. For a man with macroorchidism and mental retardation, Fragile X would be suspected, and testing focuses on the FMR1 gene CGG repeat expansion rather than a standard chromosomal study, though genetic evaluation overall would be pursued.

Chromosomal analysis is used when there’s a suspicion of a chromosomal abnormality that could explain development, anatomy, or pregnancy outcomes. A metabolic condition like phenylketonuria is diagnosed with newborn screening and biochemical testing, not by looking at chromosomes, so it would not typically prompt chromosomal analysis. In contrast, a child with multiple congenital anomalies and intellectual disability often prompts cytogenetic testing to look for deletions, duplications, or other chromosomal changes. A couple with a history of miscarriages may reveal a balanced chromosomal rearrangement in one parent, which is a common reason for parental karyotyping. For a man with macroorchidism and mental retardation, Fragile X would be suspected, and testing focuses on the FMR1 gene CGG repeat expansion rather than a standard chromosomal study, though genetic evaluation overall would be pursued.