Identification of Novel HUWE1 Variants in Turner-Type X-Linked Intellectual Disability.

Objective

To characterize the clinical phenotypes and identify the genetic etiology in four unrelated families affected by Turner-type X-linked intellectual disability (XLID).

Methods

Peripheral blood samples were collected from four probands and their parents. Genomic DNA was extracted, and a comprehensive genetic analysis was performed using trio-based Whole Exome Sequencing (WES) combined with low-pass Copy Number Variation sequencing (CNV-seq). Candidate variants were subsequently validated via Sanger sequencing.

Results

Genetic analysis identified distinct variants in the HUWE1 across the four families. Specifically, a hemizygous c.10034A>T (p.Lys3345Met) variant was identified in the proband of Family 1; a heterozygous c.9209G>A (p.Arg3070His) variant in Family 2; a heterozygous c.12688T>C (p.Phe4230Leu) variant in Family 3; and a hemizygous c.9070G>A (p.Ala3024Thr) variant in Family 4. According to the ACMG guidelines, all four variants were classified as "Likely Pathogenic" based on the following criteria: PS2 + PM2_Supporting + PP2 + PP3. Notably, the c.10034A>T (p.Lys3345Met), c.12688T>C (p.Phe4230Leu), and c.9070G>A (p.Ala3024Thr) are novel variants that have not been previously reported. All probands were clinically diagnosed with Turner-type XLID.

Conclusions

This study expands the pathogenic variant spectrum of HUWE1 and provides novel molecular evidence for the clinical diagnosis of Turner-type XLID. These findings are of significant value for genetic counseling, carrier screening, and prenatal diagnosis for the affected families.