RNA analysis of consensus sequence splicing mutations: implications for thediagnosis of Wilson disease

Wilson disease (WD) is an autosomal recessive disorder caused by a defective function of the copper-transporting ATP7B protein. This results in progressive copper overload and consequent liver, brain, and kidney damage. Approximately 300 WD-causing mutations have been described to date. Missense mutations are largely prevalent, while splice-site mutations are rarer. Of these, only a minority are detected in splicing consensus sequences. Further, few splicing mutations have been studied at the RNA level. In this study we report the RNA molecular characterization of three consensus splice-site mutations identified by DNA analysis in WD patients. One of them, c.51 + 4 A --> T, resides in the consensus sequence of the donor splice site of intron 1; the second, c. 2121 + 3 A --> G, occurred in position + 3 of intron 7; and the c.2447 + 5 G --> A is localized in the consensus sequence of the donor splice site of intron 9. Analysis revealed predominantly abnormal splicing in the samples carrying mutations compared to the normal controls. These results strongly suggest that consensus sequence splice-site mutations result in disease by interfering with the production of the normal WD protein. Our data contribute to understanding the mutational spectrum that affect splicing and improve our capability in WD diagnosis

Genetic variation spectrum in ATP7B gene identified in Latvian patients with Wilson disease

Funding Information: This study was partially financed by the grant of Riga Stradin©≤s University, Department of Doctoral studies, grant of Roche Academy, and the funds of Latvian Council of Science (No. 09.1384; No 10.0010.02 and No. 05.0023). Publisher Copyright: © 2017 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc.Background: Wilson disease (WD) is an autosomal recessive disorder of copper metabolism caused by allelic variants in ATP7B gene. More than 500 distinct variants have been reported, the most common WD causing allelic variant in the patients from Central, Eastern, and Northern Europe is H1069Q. Methods: All Latvian patients with clinically confirmed WD were screened for the most common mutation p.H1069Q by PCR Bi-PASA method. Direct DNA sequencing of gene ATP7B (all 21 exons) was performed for the patients with WD symptoms, being either heterozygous for H1069Q or without it on any allele. Results: We identified 15 different allelic variants along with eight non-disease-causing allelic variants. Based on the gene molecular analysis and patients' clinical data variant p.His1069Gln was found in 66.9% of WD alleles. Wide clinical variability was observed among individuals with the same ATP7B genotype. The results of our study confirm that neurological manifestations of WD are typically present later than the liver disease but no significant association between the presence/absence of the most common genetic variant and mode of initial WD presentation or age at presentation was identified. Conclusions: (1) The most prevalent mutation in Latvian patients with Wilson disease was c.3207C>A (p.His1069Gln); (2) No significant phenotype–genotype correlation was found in Latvian patients with Wilson disease; (3) The estimated prevalence of Wilson disease in Latvia is 1 of 24,000 cases which is higher than frequently quoted prevalence of 1: 30,000.publishersversionPeer reviewe

Resolved Psychosis after Liver Transplantation in a Patient with Wilson’s Disease

A psychiatric involvement is frequently present in Wilson’s disease. Psychiatric symptoms are sometimes the first and only manifestation of Wilson’s disease. More often a psychiatric involvement is present beside a neurologic or hepatic disease

A role of BRCA1 and BRCA2 germline mutations in breast cancer susceptibility within Sardinian population

<p>Abstract</p> <p>Background</p> <p>In recent years, numerous studies have assessed the prevalence of germline mutations in <it>BRCA1 </it>and <it>BRCA2 </it>genes in various cohorts. We here extensively investigated the prevalence and geographical distribution of <it>BRCA1-2 </it>mutations in the entire genetically-homogeneous Sardinian population. The occurrence of phenotypic characteristics which may be predictive for the presence of <it>BRCA1-2 </it>germline mutations was also evaluated.</p> <p>Methods</p> <p>Three hundred and forty-eight breast cancer patients presenting a familial recurrence of invasive breast or ovarian carcinoma with at least two affected family members were screened for <it>BRCA1-2 </it>mutations by DHPLC analysis and DNA sequencing. Association of <it>BRCA1 </it>and <it>BRCA2 </it>mutational status with clinical and pathological parameters was evaluated by Pearson's Chi-Squared test.</p> <p>Results and Conclusion</p> <p>Overall, 8 <it>BRCA1 </it>and 5 <it>BRCA2 </it>deleterious mutations were detected in 35/348 (10%) families; majority (23/35;66%) of mutations was found in <it>BRCA2 </it>gene. The geographical distribution of <it>BRCA1-2 </it>mutations was related to three specific large areas of Sardinia, reflecting its ancient history: <it>a</it>) the Northern area, linguistically different from the rest of the island (where a <it>BRCA2 c.8764_8765delAG </it>mutation with founder effect was predominant); <it>b</it>) the Middle area, land of the ancient Sardinian population (where <it>BRCA2 </it>mutations are still more common than <it>BRCA1 </it>mutations); and <it>c</it>) the South-Western area, with many Phoenician and Carthaginian locations (where <it>BRCA1 </it>mutations are prevalent). We also found that phenotypic features such as high tumor grading and lack of expression of estrogen/progesterone receptors together with age at diagnosis and presence of ovarian cancer in the family may be predictive for the presence of <it>BRCA1-2 </it>germline mutations.</p

Y-Chromosome Based Evidence for Pre-Neolithic Origin of the Genetically Homogeneous but Diverse Sardinian Population: Inference for Association Scans

The island of Sardinia shows a unique high incidence of several autoimmune diseases with multifactorial inheritance, particularly type 1 diabetes and multiple sclerosis. The prior knowledge of the genetic structure of this population is fundamental to establish the optimal design for association studies in these diseases. Previous work suggested that the Sardinians are a relatively homogenous population, but some reports were contradictory and data were largely based on variants subject to selection. For an unbiased assessment of genetic structure, we studied a combination of neutral Y-chromosome variants, 21 biallelic and 8 short tandem repeats (STRs) in 930 Sardinian males. We found a high degree of interindividual variation but a homogenous distribution of the detected variability in samples from three separate regions of the island. One haplogroup, I-M26, is rare or absent outside Sardinia and is very common (0.37 frequency) throughout the island, consistent with a founder effect. A Bayesian full likelihood analysis (BATWING) indicated that the time from the most recent common ancestor (TMRCA) of I-M26, was 21.0 (16.0–25.5) thousand years ago (KYA) and that the population began to expand 14.0 (7.8–22.0) KYA. These results suggest a largely pre-Neolithic settlement of the island with little subsequent gene flow from outside populations. Consequently, Sardinia is an especially attractive venue for case-control genome wide association scans in common multifactorial diseases. Concomitantly, the high degree of interindividual variation in the current population facilitates fine mapping efforts to pinpoint the aetiologic polymorphisms

High Differentiation among Eight Villages in a Secluded Area of Sardinia Revealed by Genome-Wide High Density SNPs Analysis

To better design association studies for complex traits in isolated populations it's important to understand how history and isolation moulded the genetic features of different communities. Population isolates should not “a priori” be considered homogeneous, even if the communities are not distant and part of a small region. We studied a particular area of Sardinia called Ogliastra, characterized by the presence of several distinct villages that display different history, immigration events and population size. Cultural and geographic isolation characterized the history of these communities. We determined LD parameters in 8 villages and defined population structure through high density SNPs (about 360 K) on 360 unrelated people (45 selected samples from each village). These isolates showed differences in LD values and LD map length. Five of these villages show high LD values probably due to their reduced population size and extreme isolation. High genetic differentiation among villages was detected. Moreover population structure analysis revealed a high correlation between genetic and geographic distances. Our study indicates that history, geography and biodemography have influenced the genetic features of Ogliastra communities producing differences in LD and population structure. All these data demonstrate that we can consider each village an isolate with specific characteristics. We suggest that, in order to optimize the study design of complex traits, a thorough characterization of genetic features is useful to identify the presence of sub-populations and stratification within genetic isolates