Transcription-associated breaks in xeroderma pigmentosum group D cells from patients with combined features of xeroderma pigmentosum and Cockayne syndrome.

Defects in the XPD gene can result in several clinical phenotypes, including xeroderma pigmentosum (XP), trichothiodystrophy, and, less frequently, the combined phenotype of XP and Cockayne syndrome (XP-D/CS). We previously showed that in cells from two XP-D/CS patients, breaks were introduced into cellular DNA on exposure to UV damage, but these breaks were not at the sites of the damage. In the present work, we show that three further XP-D/CS patients show the same peculiar breakage phenomenon. We show that these breaks can be visualized inside the cells by immunofluorescence using antibodies to either gamma-H2AX or poly-ADP-ribose and that they can be generated by the introduction of plasmids harboring methylation or oxidative damage as well as by UV photoproducts. Inhibition of RNA polymerase II transcription by four different inhibitors dramatically reduced the number of UV-induced breaks. Furthermore, the breaks were dependent on the nucleotide excision repair (NER) machinery. These data are consistent with our hypothesis that the NER machinery introduces the breaks at sites of transcription initiation. During transcription in UV-irradiated XP-D/CS cells, phosphorylation of the carboxy-terminal domain of RNA polymerase II occurred normally, but the elongating form of the polymerase remained blocked at lesions and was eventually degraded.

Two new XPD patients compound heterozygous for the same mutation demonstrate diverse clinical features.

Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are both rare autosomal recessive disorders with defects in DNA repair. They are usually distinct both clinically and genetically but in rare cases, patients exhibit the clinical characteristics of both diseases concurrently. We report two new phenotypically distinct cases of XP with additional features of CS (xeroderma pigmentosum and Cockayne syndrome crossover syndrome (XP/CS)) carrying an identical mutation (G47R) in the XPD gene within the N terminus of the protein. Both patients had clinical features of XP and CS but only one fulfilled most criteria for diagnosing CS. Unusually, patient 1 developed early skin cancer, in contrast to patient 2, who never developed any malignancies. Cells from both these patients have repair defects typical of xeroderma pigmentosum complementation group D (XPD) cells, but also had the phenotype of uncontrolled DNA breakage found specifically in XPD/CS cells and similarly reduced levels of TFIIH. Despite these similarities between our two patients, their clinical features are quite different and the clinical severity correlates with other cellular responses to ultraviolet irradiation.

Diabetic lipemia with eruptive xanthomatosis in a lean young female with apolipoprotein E4/4.

Eruptive xanthomas in adults are usually indicative of chylomicronemia. Although diabetes mellitus is the most common secondary cause of chylomicronemia, which is designated as diabetic lipemia, the clinical characteristics of diabetes with regard to development of xanthomas are not well defined. In this paper, we describe a young female who displayed eruptive xanthomas as an initial manifestation of diabetic lipemia. The patient was a 20-year-old female with a body mass index of 18.9 kg/m2 and Marfanoid appearance. Her past history was unremarkable, except for patent ductus arteriosus and mild mental retardation. She was admitted to our division for eruptive xanthomas on the extremities and marked hyperglycemia (random glucose, 520 mg/dl) and hypertriglyceridemia (6880 mg/dl). She was diagnosed with Type 2 diabetes based on the positive family history of diabetes, residual secretory capacity of insulin, and absence of autoantibodies related to Type 1 diabetes. Based on the increase in the concentrations of both chylomicrons and very low density lipoproteins, type V hyperlipoproteinemia was diagnosed. After the initiation of insulin therapy, both hypertriglyceridemia and eruptive xanthomas subsided, without administering any hypolipidemic agents. Minimal model analysis of a frequently sampled intravenous glucose tolerance test revealed severe insulin resistance, despite the absence of obesity. Post-heparin lipoprotein lipase (LPL) activity was moderately decreased, and common mutations in the LPL gene were not demonstrated by genetic screening. The apolipoprotein E phenotype was E4/4, which is known to be associated with type V hyperlipoproteinemia. Hypoadiponectinemia of 1.7 microg/ml was also revealed, which may, in part, account for the insulin resistance and decreased LPL activity. In conclusion, the clustering of apolipoprotein E4/4 and hypoadiponectinemia, in addition to insulin resistance and poor glycemic control, might have resulted in hypertriglyceridemia with eruptive xanthomatosis in this subject.

Genetic aspects of the vascular type of Ehlers-Danlos syndrome (vEDS, EDSIV) in Japan.

BACKGROUND: The vascular type of Ehlers-Danlos syndrome (vEDS, EDS type IV; MIM#130050) is an autosomal dominantly inherited disorder that results from mutations in the genes for type III procollagen (COL3A1). Affected individuals with vEDS are at risk of arterial rupture, aneurysm, and/or dissection; gastrointestinal perforation or rupture; and uterine rupture during pregnancy, which may lead to sudden death. METHODS AND RESULTS: Three unrelated Japanese individuals who exhibited symptoms of vEDS were analyzed. In order to identify mutations in the patients' RNA, one 3.8-kb reverse transcriptase polymerase chain reaction product containing the triple-helical domain of COL3A1 was prepared from cultured skin fibroblasts and then was sequenced directly. Three heterozygous mutations were identified; specifically, 2 novel missense base substitutions (Gly220Trp, Gly448Glu) in the (Gly-X-Y)n repeat of the triple-helical domain and a known splicing donor mutation of intron 20 (G+1, IVS20) of COL3A1. The genotype-phenotype correlations in Japanese vEDS individuals with COL3A1 mutations were also investigated. CONCLUSION: There was no association between the type of complications in vEDS and the related COL3A1 mutation found. After the genetic diagnosis of COL3A1, the establishment of both a network among medical specialists, including clinical geneticists to perform genetic counseling, and long-term follow-up systems of vEDS may help to improve the management of vascular and visceral complications.