Dataset Information

Whole-exome sequencing identifies ADRA2A mutation in atypical familial partial lipodystrophy.

ABSTRACT: Despite identification of causal genes for various lipodystrophy syndromes, the molecular basis of some peculiar lipodystrophies remains obscure. In an African-American pedigree with a novel autosomal dominant, atypical familial partial lipodystrophy (FPLD), we performed linkage analysis for candidate regions and whole-exome sequencing to identify the disease-causing mutation. Affected adults reported marked loss of fat from the extremities, with excess fat in the face and neck at age 13-15 years, and developed metabolic complications later. A heterozygous g.112837956C>T mutation on chromosome 10 (c.202C>T, p.Leu68Phe) affecting a highly conserved residue in adrenoceptor α 2A (ADRA2A) was found in all affected subjects but not in unaffected relatives. ADRA2A is the main presynaptic inhibitory feedback G protein-coupled receptor regulating norepinephrine release. Activation of ADRA2A inhibits cAMP production and reduces lipolysis in adipocytes. As compared with overexpression of a wild-type ADRA2A construct in human embryonic kidney-293 cells and differentiated 3T3-L1 adipocytes, the mutant ADRA2A produced more cAMP and glycerol, which were resistant to the effects of the α2-adrenergic receptor agonist clonidine and the α2-adrenergic receptor antagonist yohimbine, suggesting loss of function. We conclude that heterozygous p.Leu68Phe ADRA2A mutation causes a rare atypical FPLD, most likely by inducing excessive lipolysis in some adipose tissue depots.

SUBMITTER: Garg A

PROVIDER: S-EPMC4927009 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:BackgroundGenetic association studies for gastroschisis have highlighted several candidate variants. However, genetic basis in gastroschisis from noninvestigated heritable factors could provide new insights into the human biology for this birth defect. We aim to identify novel gastroschisis susceptibility variants by employing whole exome sequencing (WES) in a Mexican family with recurrence of gastroschisis.MethodsWe employed WES in two affected half-sisters with gastroschisis, mother, and father of the proband. Additionally, functional bioinformatics analysis was based on SVS-PhoRank and Ensembl-Variant Effect Predictor. The latter assessed the potentially deleterious effects (high, moderate, low, or modifier impact) from exome variants based on SIFT, PolyPhen, dbNSFP, Condel, LoFtool, MaxEntScan, and BLOSUM62 algorithms. The analysis was based on the Human Genome annotation, GRCh37/hg19. Candidate genes were prioritized and manually curated based on significant phenotypic relevance (SVS-PhoRank) and functional properties (Ensembl-Variant Effect Predictor). Functional enrichment analysis was performed using ToppGene Suite, including a manual curation of significant Gene Ontology (GO) biological processes from functional similarity analysis of candidate genes.ResultsNo single gene-disrupting variant was identified. Instead, 428 heterozygous variations were identified for which SPATA17, PDE4DIP, CFAP65, ALPP, ZNF717, OR4C3, MAP2K3, TLR8, and UBE2NL were predicted as high impact in both cases, mother, and father of the proband. PLOD1, COL6A3, FGFRL1, HHIP, SGCD, RAPGEF1, PKD1, ZFHX3, BCAS3, EVPL, CEACAM5, and KLK14 were segregated among both cases and mother. Multiple interacting background modifiers may regulate gastroschisis susceptibility. These candidate genes highlight a role for development of blood vessel, circulatory system, muscle structure, epithelium, and epidermis, regulation of cell junction assembly, biological/cell adhesion, detection/response to endogenous stimulus, regulation of cytokine biosynthetic process, response to growth factor, postreplication repair/protein K63-linked ubiquitination, protein-containing complex assembly, and regulation of transcription DNA-templated.ConclusionConsidering the likely gene-disrupting prediction results and similar biological pattern of mechanisms, we propose a joint "multifactorial model" in gastroschisis pathogenesis.

Project description:Primary immunodeficiency disorders (PIDs) render patients vulnerable to infection with a wide range of microorganisms and thus provide good in vivo models for the assessment of immune responses during infectious challenges. Priming of the immune system, especially in infancy, depends on different environmental exposures and medical practices. This may determine the timing and phenotype of clinical appearance of immune deficits as exemplified with early exposure to Bacillus Calmette-Guérin (BCG) vaccination and dissemination in combined immunodeficiencies. Varied phenotype expression poses a challenge to identification of the putative immune deficit. Without the availability of genomic diagnosis and data analysis resources and with limited capacity for functional definition of immune pathways, it is difficult to establish a definitive diagnosis and to decide on appropriate treatment. This study describes the use of exome sequencing to identify a homozygous recessive variant in MAP3K14, NIKVal345Met, in a patient with combined immunodeficiency, disseminated BCG-osis, and paradoxically elevated lymphocytes. Laboratory testing confirmed hypogammaglobulinemia with normal CD19, but failed to confirm a definitive diagnosis for targeted treatment decisions. NIKVal345Met is predicted to be deleterious and pathogenic by two in silico prediction tools and is situated in a gene crucial for effective functioning of the non-canonical nuclear factor-kappa B signaling pathway. Functional analysis of NIKVal345Met- versus NIKWT-transfected human embryonic kidney-293T cells showed that this mutation significantly affects the kinase activity of NIK leading to decreased levels of phosphorylated IkappaB kinase-alpha (IKK?), the target of NIK. BCG-stimulated RAW264.7 cells transfected with NIKVal345Met?also presented with reduced levels of phosphorylated IKK?, significantly increased p100 levels and significantly decreased p52 levels compared to cells transfected with NIKWT. Ideally, these experiments would have been conducted in patient-derived immune cells, but we were unable to source these cells from the patient. The functional analysis described in this paper supports previous illustrations of the importance of NIK in human immune responses and demonstrates the involvement of function-altering mutations in MAP3K14 in PIDs. The genomic approach used for this patient demonstrates its value in the diagnosis of an unusual PID and as a tool for detecting rarer mutations to help guide treatment approaches.

Dataset Information

Whole-exome sequencing identifies ADRA2A mutation in atypical familial partial lipodystrophy.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets