Turner Syndrome with Isochromosome Xq

Area of Science:

• Genetics
• Endocrinology
• Pediatrics

Background:

• Turner syndrome (TS) is a chromosomal condition affecting females, often characterized by short stature and growth retardation.
• Mosaic karyotypes, where cells have different chromosome compositions, can lead to varied TS phenotypes.
• Understanding these variations is crucial for accurate diagnosis and management.

Observation:

• A 19-year-old female presented with primary amenorrhea and growth retardation.
• Her karyotype revealed a mosaic pattern: 46,X,i(Xq) in 17 cells and 45,X in 8 cells.
• This specific mosaic karyotype, 46,X,i(Xq), is considered a variant cause of Turner syndrome.

Findings:

• The patient exhibited normal social and psychomotor development, contrasting with some classic TS presentations.
• Clinical and laboratory findings were compared to the classic description of Turner syndrome.
• The i(Xq) chromosome (isochromosome of the long arm of X) was present in a mosaic state.

Implications:

• This case expands the phenotype-genotype correlation for Turner syndrome, particularly for mosaic variants.
• It emphasizes that variant karyotypes can present with less severe neurodevelopmental outcomes.
• Further research into mosaic Turner syndrome is warranted to fully delineate its clinical spectrum.