H-Y antigen negativity associated with a normal male phenotype

Area of Science:

• Genetics
• Reproductive Biology
• Human Genetics

Background:

• Sex chromosome mosaicism, particularly 45,X/46,XY, is a rare condition with a wide range of clinical presentations.
• Phenotypes can vary from female characteristics to mixed gonadal dysgenesis, hermaphroditism, or nearly normal males.
• Rearrangements of the Y chromosome, such as isochromosome Y (i(Y)), dicentric Y (dic(Y)), deletion Y (del(Y)), and ring Y (r(Y)), are common in these cases.

Observation:

• A rare case of 45,X/46,X,Y-f (Y-fragment) mosaicism was identified in a phenotypically normal male.
• The individual presented with sterility and was HY antigen-negative.
• The Y-fragment (Y-f) was presumed to be a small deletion on the Y chromosome (del(Yq)).

Findings:

• The study reports a unique case of a phenotypically normal but sterile male with a 45,X/46,X,Y-f karyotype.
• This individual was found to be HY antigen-negative, which is significant given the presence of Y chromosome material.
• The Y-fragment (Y-f) in the 46,X,Y-f cell line is likely a small deletion on the Y chromosome, potentially affecting fertility and HY antigen expression.

Implications:

• This case contributes to understanding the phenotypic variability and genetic basis of 45,X/46,XY mosaicism.
• It highlights the importance of detailed cytogenetic analysis in cases of male infertility and sexual ambiguity.
• Further research into the specific genetic components of Y-fragment (Y-f) and their role in HY antigen expression and fertility is warranted.