Complex X chromosome rearrangement associated with multiorgan autoimmunity

Area of Science:

• Genetics
• Immunology
• Reproductive Biology

Background:

• Turner syndrome, affecting 1/2,500 births, results from X chromosome abnormalities and is typically associated with short stature and gonadal dysgenesis.
• While 45,X karyotype is common, mosaicism and structural X chromosome abnormalities also occur.
• Complex intra-X chromosomal rearrangements are exceptionally rare.

Observation:

• A unique case of a complex X chromosome rearrangement was found in a young female with multiple autoimmune diseases, including diabetes and Hashimoto's thyroiditis.
• Genetic analysis revealed single copy of Xp, three copies of two Xq segments, and two copies of an Xq27.3 region.
• Skewed X inactivation (70:30 methylated/unmethylated) and a rearranged paternal X chromosome were identified.

Findings:

• The complex X chromosome rearrangement involved multiple breakpoints, fusions, and inverted duplication, resembling a "shattered" i(Xq) chromosome.
• Despite the complex rearrangement, the patient lacked classic Turner syndrome somatic features.
• The patient presented with a wide spectrum of autoimmune disorders, including insulin-dependent diabetes mellitus, Hashimoto's thyroiditis, and celiac disease.

Implications:

• The fragmentation of the i(Xq) chromosome appears to elevate the risk for developing multiorgan autoimmune diseases.
• This case highlights a potential link between complex X chromosome structural variations and autoimmune conditions.
• Further research into X chromosome rearrangements and their impact on immune system regulation is warranted.