Copy number variation analysis detects novel candidate genes involved in follicular growth and oocyte maturation in a cohort of premature ovarian failure cases.

STUDY QUESTION: Can spontaneous premature ovarian failure (POF) patients derived from population-based biobanks reveal the association between copy number variations (CNVs) and POF? SUMMARY ANSWER: CNVs can hamper the functional capacity of ovaries by disrupting key genes and pathways essential for proper ovarian function. WHAT IS KNOWN ALREADY: POF is defined as the cessation of ovarian function before the age of 40 years. POF is a major reason for female infertility, although its cause remains largely unknown. STUDY DESIGN, SIZE, DURATION: The current retrospective CNV study included 301 spontaneous POF patients and 3188 control individuals registered between 2003 and 2014 at Estonian Genome Center at the University of Tartu (EGCUT) biobank. PARTICIPANTS/MATERIALS, SETTING, METHODS: DNA samples from 301 spontaneous POF patients were genotyped by Illumina HumanCoreExome (258 samples) and HumanOmniExpress (43 samples) BeadChip arrays. Genotype and phenotype information was drawn from the EGCUT for the 3188 control population samples, previously genotyped with HumanCNV370 and HumanOmniExpress BeadChip arrays. All identified CNVs were subjected to functional enrichment studies for highlighting the POF pathogenesis. Real-time quantitative PCR was used to validate a subset of CNVs. Whole-exome sequencing was performed on six patients carrying hemizygous deletions that encompass genes essential for meiosis or folliculogenesis. MAIN RESULTS AND THE ROLE OF CHANCE: Eleven novel microdeletions and microduplications that encompass genes relevant to POF were identified. For example, FMN2 (1q43) and SGOL2 (2q33.1) are essential for meiotic progression, while TBP (6q27), SCARB1 (12q24.31), BNC1 (15q25) and ARFGAP3 (22q13.2) are involved in follicular growth and oocyte maturation. The importance of recently discovered hemizygous microdeletions of meiotic genes SYCE1 (10q26.3) and CPEB1 (15q25.2) in POF patients was also corroborated. LIMITATIONS, REASONS FOR CAUTION: This is a descriptive analysis and no functional studies were performed. Anamnestic data obtained from population-based biobank lacked clinical, biological (hormone levels) or ultrasonographical data, and spontaneous POF was predicted retrospectively by excluding known extraovarian causes for premature menopause. WIDER IMPLICATIONS OF THE FINDINGS: The present study, with high number of spontaneous POF cases, provides novel data on associations between the genomic aberrations and premature menopause of ovarian cause and demonstrates that population-based biobanks are powerful source of biological samples and clinical data to reveal novel genetic lesions associated with human reproductive health and disease, including POF. STUDY FUNDING/COMPETING INTEREST: This study was supported by the Estonian Ministry of Education and Research (IUT20-43, IUT20-60, IUT34-16, SF0180027s10 and 9205), Enterprise Estonia (EU30020 and EU48695), Eureka's EUROSTARS programme (NOTED, EU41564), grants from European Union's FP7 Marie Curie Industry-Academia Partnerships and Pathways (IAPP, SARM, |EU324509) and Horizon 2020 innovation programme (WIDENLIFE, 692065), Academy of Finland and the Sigrid Juselius Foundation.

ITPR1 gene p.Val1553Met mutation in Russian family with mild Spinocerebellar ataxia.

BACKGROUND: Spinocerebellar ataxias (SСAs) are a highly heterogeneous group of inherited neurological disorders. The symptoms of ataxia vary in individual patients and even within the same SCA subtype. A study of a four-generation family with autosomal dominant (AD) non-progressive SCA with mild symptoms was conducted. The genotyping of this family revealed no frequent pathogenic mutations. So the objective of this study was to identify the genetic causes of the disease in this family with the technology of whole-exome sequencing (WES). METHODS AND RESULTS: WES, candidate variant analysis with further Sanger sequencing, mRNA secondary structure prediction, and RSCU analysis were performed; a heterozygous missense mutation in ITPR1 was identified. CONCLUSION: Our study confirms the fact that ITPR1 gene plays a certain role in the pathogenesis of SCAs, and, therefore, we suggest that c.4657G>A p.Val1553Met) is a disease-causing mutation in the family studied.

A missense mutation in DUSP6 is associated with Class III malocclusion.

Class III malocclusion is a common dentofacial phenotype with a variable prevalence according to ethnic background. The etiology of Class III malocclusion has been attributed mainly to interactions between susceptibility genes and environmental factors during the morphogenesis of the mandible and maxilla. Class III malocclusion shows familial recurrence, and family-based studies support a predominance of an autosomal-dominant mode of inheritance. We performed whole-exome sequencing on five siblings from an Estonian family affected by Class III malocclusion. We identified a rare heterozygous missense mutation, c.545C>T (p.Ser182Phe), in the DUSP6 gene, a likely causal variant. This variant co-segregated with the disease following an autosomal-dominant mode of inheritance with incomplete penetrance. Transcriptional activation of DUSP6 has been presumed to be regulated by FGF/FGFR and MAPK/ERK signaling during fundamental processes at early stages of skeletal development. Several candidate genes within a linkage region on chromosome 12q22-q23--harboring DUSP6--are implicated in the regulation of maxillary or mandibular growth. The current study reinforces that the 12q22-q23 region is biologically relevant to craniofacial development and may be genetically linked to the Class III malocclusion.