(A–D) Microcephaly without enophthalmos; lentigines on face, posterior neck, and dorsum of hands (black arrows). (E) Scar from blistering sunburn 6 months after UVB-phototesting (red box). (F and G) XP140BR cells are NER-deficient. 1BR (normal control), XP140BR (XP-J), XP15BR (XP-A); 20J/m² UVC-irradiation (F). 15J/m² UVC-irradiation (G). (H) XP140BR is not complemented by known XP cDNAs, but is rescued by GTF2H4. 20J/m² UVC-irradiation. Bars and error bars represent means and SEM, respectively, of experiments (n = 3–4, as indicated by the colored circles and their corresponding plots). (I) GTF2H4 structure and mutations. (J) TFIIH-p52 subunit, encoded by GTF2H4, is C-terminally truncated in the patient, but still forms a stable complex. Left, immunoblots of major TFIIH-subunits (SMC3, loading control); Middle, schematic of TFIIH-subunit interactions; Right, XP genes associated with TFIIH-subunits (references in Supplemental Table 1).