Turner syndrome caused by rare complex structural abnormalities involving chromosome X

Area of Science:

• Genetics
• Human Genetics
• Molecular Genetics

Background:

• Turner syndrome (TS) is a genetic disorder affecting females, characterized by X-chromosome abnormalities and diverse clinical features.
• While 45,X is common, mosaicism and structural X-chromosome abnormalities like deletions and duplications also cause TS.
• Understanding these complex karyotypes is crucial for accurate diagnosis and genetic counseling.

Purpose of the Study:

• To report and analyze the genotype-phenotype correlations in two Chinese female patients with rare Turner syndrome karyotypes.
• To investigate complex X-chromosome structural abnormalities using chromosome microarray analysis (CMA).
• To provide novel insights into the genetic basis of Turner syndrome.

Main Methods:

• Chromosome microarray analysis (CMA) was performed on two female TS patients with unusual karyotypes.
• Detailed analysis of deletions and duplications on the X-chromosome was conducted.
• Genotype-phenotype correlation was established for both patients.

Main Results:

• Patient 1 (46,X,der(X)) exhibited three deletions and three duplications on the X-chromosome.
• Patient 2 (46,X,der(X)t(X;?)(q22.1;?),inv(11)(q13.5q21)) showed an Xq21.2-q27.1 duplication and an Xq27.2-q28 deletion.
• These findings highlight the heterogeneity of X-chromosomal abnormalities in TS.

Conclusions:

• CMA is effective in characterizing complex X-chromosome rearrangements in Turner syndrome.
• The identified unique deletions and duplications contribute to a deeper understanding of TS genotypes.
• This study enhances genotype-phenotype correlation knowledge for rare TS cases.