ERCC2 mutations in two siblings with a severe trichothiodystrophy phenotype

TFIIH central activity in nucleotide excision repair to prevent disease

The heterodecameric transcription factor IIH (TFIIH) functions in multiple cellular processes, foremost in nucleotide excision repair (NER) and transcription initiation by RNA polymerase II. TFIIH is essential for life and hereditary mutations in TFIIH cause the devastating human syndromes xeroderma pigmentosum, Cockayne syndrome or trichothiodystrophy, or combinations of these. In NER, TFIIH binds to DNA after DNA damage is detected and, using its translocase and helicase subunits XPB and XPD, opens up the DNA and checks for the presence of DNA damage. This central activity leads to dual incision and removal of the DNA strand containing the damage, after which the resulting DNA gap is restored. In this review, we discuss new structural and mechanistic insights into the central function of TFIIH in NER. Moreover, we provide an elaborate overview of all currently known patients and diseases associated with inherited TFIIH mutations and describe how our understanding of TFIIH function in NER and transcription can explain the different disease features caused by TFIIH deficiency.

Novel ERCC2 variant in trichothiodystrophy infant: the first case report in China

BACKGROUND

Trichothiodystrophy (TTD) is a rare, autosomal recessive, multisystem disorder most commonly caused by variants in ERCC2.

CASE PRESENTATION

Here, we describe the first Chinese patient with a novel variant in ERCC2. A male infant, who was born to a healthy non-consanguineous couple, exhibited brittle hair, hair loss ichthyosis, eczema, retinal pigmentation and hypospadias. He carried a novel heterozygous ERCC2 variant. The maternal variant (c.2191-18_2213del) is a previous described genomic deletion that affects the splicing of intron 22. The paternal variant (c.1666-1G > A), that occurs in the splice site of intron 17 and likely alters ERCC2 gene function through aberrant splicing, has not been reported previously.

CONCLUSIONS

Our case reported a novel pathogenic variant in ERCC2, which expanded the known genetic variants associated with TTD.