Pseudouridylation defect due to DKC1 and NOP10 mutations causes nephrotic syndrome with cataracts, hearing impairment, and enterocolitis.

RNA modifications play a fundamental role in cellular function. Pseudouridylation, the most abundant RNA modification, is catalyzed by the H/ACA small ribonucleoprotein (snoRNP) complex that shares four core proteins, dyskerin (DKC1), NOP10, NHP2, and GAR1. Mutations in DKC1, NOP10, or NHP2 cause dyskeratosis congenita (DC), a disorder characterized by telomere attrition. Here, we report a phenotype comprising nephrotic syndrome, cataracts, sensorineural deafness, enterocolitis, and early lethality in two pedigrees: males with DKC1 p.Glu206Lys and two children with homozygous NOP10 p.Thr16Met. Females with heterozygous DKC1 p.Glu206Lys developed cataracts and sensorineural deafness, but nephrotic syndrome in only one case of skewed X-inactivation. We found telomere attrition in both pedigrees, but no mucocutaneous abnormalities suggestive of DC. Both mutations fall at the dyskerin-NOP10 binding interface in a region distinct from those implicated in DC, impair the dyskerin-NOP10 interaction, and disrupt the catalytic pseudouridylation site. Accordingly, we found reduced pseudouridine levels in the ribosomal RNA (rRNA) of the patients. Zebrafish dkc1 mutants recapitulate the human phenotype and show reduced 18S pseudouridylation, ribosomal dysregulation, and a cell-cycle defect in the absence of telomere attrition. We therefore propose that this human disorder is the consequence of defective snoRNP pseudouridylation and ribosomal dysfunction.

Sequencing of Chromosomal Locus 6q25.1 Revealed Two Significant SNPs rs2046210 and rs2046211 Associated with Breast Cancer: A Case-Control Study in Egyptian Women.

BACKGROUND: Breast cancer (BC) is one of the major health problems affecting females in Egypt. Certain chromosomal loci abnormalities were proved to be associated with BC in different populations. One of them is chromosomal locus 6q25.1, that affects estrogen receptor gene (ESR) which controls ER receptor expression. Therefore, the aim of this study was to investigate locus 6q25.1 among group of Egyptian female BC patients and compare the results to healthy matched age controls. METHODS: Formalin fixed paraffin embedded (FFPE) samples of sixty newly diagnosed BC patients were sequenced for locus 6q25.1 using genetic analyzer with capillary electrophoresis (3500 GA). The identified single nucleotide polymorphisms (SNPs) were compared to blood samples of forty controls. Realtime PCR using TaqMan probes was used for validation. RESULTS: Two SNPs rs2046210 and rs2046211 were significantly associated with BC. Frequency of rs2046210-A minor allele was 30% in controls, while the frequency of rs2046211-G minor allele was 15%. Rs2046210-A allele was associated with increased risk of BC (P=0.0001), while rs2046211-G allele was associated with reduced risk of BC (P=0.021). Combined analysis of both SNPs showed that haplotype A/C was associated with increased risk of BC (P = 0.042). No significant correlation was found between rs2046210-A allele and ER status, while positive association was observed between rs204621-C allele and ER status (p= 0.005). CONCLUSION: Our data confirmed the important association between locus 6q25.1 and risk of BC in other populations. The frequencies of minor alleles of both significant SNPs will pave the way for a wider large-scale genome study and to be investigated with other BC risk factors.

Mutations in LAMB2 Are Associated With Albuminuria and Optic Nerve Hypoplasia With Hypopituitarism.

CONTEXT: Mutations in LAMB2, encoding the basement membrane protein, laminin ß2, are associated with an autosomal recessive disorder characterized by congenital nephrotic syndrome, ocular abnormalities, and neurodevelopmental delay (Pierson syndrome). CASE DESCRIPTION: This report describes a 12-year-old boy with short stature, visual impairment, and developmental delay who presented with macroscopic hematuria and albuminuria. He had isolated growth hormone deficiency, optic nerve hypoplasia, and a small anterior pituitary with corpus callosum dysgenesis on his cranial magnetic resonance imaging, thereby supporting a diagnosis of optic nerve hypoplasia syndrome. Renal histopathology revealed focal segmental glomerulosclerosis. Using next-generation sequencing on a targeted gene panel for steroid-resistant nephrotic syndrome, compound heterozygous missense mutations were identified in LAMB2 (c.737G>A p.Arg246Gln, c.3982G>C p.Gly1328Arg). Immunohistochemical analysis revealed reduced glomerular laminin ß2 expression compared to control kidney and a thin basement membrane on electron microscopy. Laminin ß2 is expressed during pituitary development and Lamb2-/- mice exhibit stunted growth, abnormal neural retinae, and here we show, abnormal parenchyma of the anterior pituitary gland. CONCLUSION: We propose that patients with genetically undefined optic nerve hypoplasia syndrome should be screened for albuminuria and, if present, screened for mutations in LAMB2.

Role of the von Willebrand factor and the VITRO score as predictors for variceal bleeding in patients with hepatitis C-related cirrhosis.

BACKGROUND: Noninvasive methods have been established to detect clinically significant portal hypertension in liver cirrhosis with variable limitations. The von Willebrand factor (vEF) has been found to increase in liver cirrhosis. AIM: The aim of this study was to explore the vEF and VITRO (von Willebrand factor antigen/platelet ratio) score in the prediction of variceal bleeding in patients with portal hypertension. MATERIALS AND METHODS: Fifty patients with hepatitis C-related liver cirrhosis (25 patients with variceal bleeding and 25 without variceal bleeding) as well as 80 healthy controls were included. Laboratory investigations and upper gastrointestinal endoscopy were performed in all patients. Serum vEF was measured in the patient and the control group. The VITRO score was calculated. RESULTS: The mean levels of the vEF antigen and the VITRO score were higher in patients with variceal bleeding compared with patients without variceal bleeding and controls (P<0.001). At levels of at least 100.1 ng/ml and at least 0.732, the vEF and the VITRO score could predict variceal bleeding with a sensitivity and a specificity of 92 and 99.9% for the vEF and 80 and 68% for the VITRO score (area under the curve=0.982 and 0.843), respectively. Levels of vEF were correlated positively with esophageal varices grade. CONCLUSION: Serum vEF level and the VITRO score are potential noninvasive biomarkers for the prediction and risk stratification of variceal bleeding in hepatitis C-related liver cirrhosis.

Cardiac matrix remodelling in congestive heart failure: the role of matrix metalloproteinases.

BACKGROUND: Congestive heart failure (CHF), the most frequent reason for hospital admission of elderly patients, is an important and rapidly increasing cause of morbidity and mortality worldwide. Its development is accompanied by left-ventricle (LV) dilatation and pump dysfunction. The extracellular space in the heart is now recognized as an essential element of myocardial structure and function, and a dynamic participant in remodelling. The matrix metalloproteinases (MMPs) are an endogenous enzyme system responsible for extracellular collagen degradation and remodelling. OBJECTIVES: To evaluate the potential role of several MMPs (MMP-1, MMP-3 and MMP-9) in CHF. PATIENTS AND METHODS: We recruited 30 consecutive patients with moderate to severe CHF who presented for heart-failure management, along with 15 age- and sex-matched control participants. Two-dimensional and M-mode echocardiographic studies were used to assess LV size and function and hence assess LV remodelling. MMP-1, -3 and -9 concentrations in serum were measured by ELISA at the time of admission and diagnosis. RESULTS: Serum levels of all 3 metalloproteinases were higher in patients with CHF than in controls; those of MMP-3 were markedly increased in patients with severe CHF. CONCLUSIONS: The association found between LV performance and MMP levels suggests that MMPs are implicated in CHF, that serum concentrations of MMPs may serve as markers for CHF, and that MMPs are a potential novel therapeutic target.