Novel RNF113A Variant Underlying X-Linked Trichothiodystrophy With Presumed Mosaicism in an Unaffected Mother
January 2026
in “
American Journal of Medical Genetics Part A
”
Studysummary The researchers reported two brothers with a new variant of X-linked trichothiodystrophy associated with an RNF113A gene mutation, highlighting features such as intellectual disability and growth failure, but without previously reported endocrinological or genital abnormalities, underlining the importance of genetic counseling for such variants.
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This case report describes two brothers in their 30s with a novel hemizygous variant c.635G>A p.Gly212Asp in the RNF113A gene, associated with X-linked trichothiodystrophy (TTD). The brothers exhibit features consistent with TTD, such as intellectual disability, microcephaly, growth failure, dysmorphic features, severe myopia, and a tiger-tail banding pattern in their hair. However, they do not show endocrinological abnormalities, recurrent infections, genital abnormalities, or abnormal MRI findings, indicating these are not universal features of RNF113A-related TTD. The variant was not found in their mother's tested tissues, suggesting she may have low-level somatic or germline mosaicism. This case underscores the importance of genetic counseling and reproductive testing for families with presumed de novo variants.
