Heteromorphic X chromosomes in 46,XX males?

Area of Science:

• Genetics
• Human Biology
• Chromosomal Abnormalities

Background:

• XX males are individuals with a male phenotype but possess two X chromosomes.
• The etiology of XX males is complex and may involve Y-chromosome material translocated onto an X chromosome.

Purpose of the Study:

• To investigate the presence of an elongated short arm of the X chromosome (XXp+) in XX males.
• To determine if chromosomal length differences correlate with the XX male phenotype.

Main Methods:

• Blind comparison of G-banded mitoses from XX males and control females.
• Quantitative measurement of X chromosome arms from XX males, XXY males, and controls.
• Statistical analysis of chromosomal measurements.

Main Results:

• Ocular inspection of photomicrographs suggested a potential XXp+ phenomenon in some XX males, but results were ambiguous.
• Detailed chromosomal measurements failed to confirm any significant increase in the length of the X chromosome short arm (XXp+) in XX males.
• Statistical analysis showed no difference in Xp arm lengths between XX males and controls.

Conclusions:

• The study did not find evidence for an XXp+ phenomenon in the tested XX males.
• Discrepancies between visual assessment and measurement may be due to alterations in band shape or staining, not length.
• The findings support the hypothesis that the causes of XX male syndrome are diverse.