Project description:PurposeThis study reports the ophthalmic and genetic findings of a Cameroonian patient with autosomal recessive retinitis pigmentosa (arRP) caused by a novel Receptor Expression Enhancing Protein 6 (REEP6) homozygous mutation.Patient and methodsA 33-year-old man underwent comprehensive ophthalmic examinations, including visual acuity measurements, dilated fundus imaging, electroretinography (ERG), and spectral-domain optical coherence tomography (SD-OCT). Short-wavelength fundus autofluorescence (SW-AF) and near-infrared fundus autofluorescence (NIR-AF) were also evaluated. Whole exome sequencing (WES) was used to identify potential pathogenic variants.ResultsFundus examination revealed typical RP findings with additional temporal ten micron yellow dots. SD-OCT imaging revealed cystoid macular edema and perifoveal outer retinal atrophy with centrally preserved inner segment ellipsoid zone (EZ) bands. Hyperreflective spots were seen in the inner retinal layers. On SW-AF images, a hypoautofluorescent area in the perifoveal area was observed. NIR-AF imaging revealed an irregularly shaped hyperautofluorescent ring. His visual acuity was mildly affected. ERG showed undetectable rod responses and intact cone responses. Genetic testing via WES revealed a novel homozygous mutation (c.295G>A, p.Glu99Lys) in the gene encoding REEP6, which is predicted to alter the charge in the transmembrane helix.ConclusionsThis report is not only the first description of a Cameroonian patient with arRP associated with a REEP6 mutation, but also this particular genetic alteration. Substitution of p.Glu99Lys in REEP6 likely disrupts the interactions between REEP6 and the ER membrane. NIR-AF imaging may be particularly useful for assessing functional photoreceptor cells and show an "avocado" pattern of hyperautofluorescence in patients with the REEP6 mutation.
Project description:BackgroundHemophagocytic Lymphohistiocytosis (HLH) is a life-threatening immunodeficiency and multi-organ disease that affects people of all ages and ethnic groups. Common symptoms and signs of this disease are high fever, hepatosplenomegaly, and cytopenias. Familial form of HLH disease, which is an autosomal recessive hematological disorder is due to disease-causing mutations in several genes essential for NK and T-cell granule-mediated cytotoxic function. For an effective cytotoxic response from cytotoxic T lymphocyte or NK cell encountering an infected cell or tumor cell, different processes are required, including trafficking, docking, priming, membrane fusion, and entry of cytotoxic granules into the target cell leading to apoptosis. Therefore, genes involved in these steps play important roles in the pathogenesis of HLH disease which include PRF1, UNC13D (MUNC13-4), STX11, and STXBP2 (MUNC18-2).Case presentationHere, we report a novel missense mutation in an 8-year-old boy suffered from hepatosplenomegaly, hepatitis, epilepsy and pancytopenia. The patient was born to a first-cousin parents with no previous documented disease in his parents. To identify mutated gene in the proband, Whole Exome Sequencing (WES) utilizing next generation sequencing was used on an Illumina HiSeq 2000 platform on DNA sample from the patient. Results showed a novel deleterious homozygous missense mutation in PRF1 gene (NM_001083116: exon3: c. 1120 T > G, p.W374G) in the patient and then using Sanger sequencing it was confirmed in the proband and his parents. Since his parents were heterozygous for the identified mutation, autosomal recessive pattern of inheritance was confirmed in the family.ConclusionsOur study identified a rare new pathogenic missense mutation in PRF1 gene in patient with HLH disease and it is the first report of mutation in PRF1 in Iranian patients with this disease.
Project description:Hereditary defects in tooth enamel formation, amelogenesis imperfecta (AI), can be non-syndromic or syndromic phenotype. Integrins are signaling proteins that mediate cell-cell and cell-extracellular matrix communication, and their involvement in tooth development is well known. The purposes of this study were to identify genetic cause of an AI family and molecular pathogenesis underlying defective enamel formation.We recruited a Turkish family with isolated AI and performed mutational analyses to clarify the underlying molecular genetic etiology.Autozygosity mapping and exome sequencing identified a novel homozygous ITGB6 transversion mutation in exon 4 (c.517G>C, p.Gly173Arg). The glycine at this position in the middle of the ?I-domain is conserved among a wide range of vertebrate orthologs and human paralogs. Clinically, the enamel was generally thin and pitted with pigmentation. Thicker enamel was noted at the cervical area of the molars.In this study, we identified a novel homozygous ITGB6 mutation causing isolated AI, and this advances the understanding of normal and pathologic enamel development.
Project description:BackgroundAutosomal recessive primary microcephaly (MCPH) is a rare genetically heterogeneous disorder of neurogenic brain development characterized by a reduced head circumference at birth with no remarkable anomalies of brain architecture and variable degrees of intellectual impairment. Clinical and genetic heterogeneity in genetic disorders represent a major diagnostic challenge.Case presentationTwo patients, 11 and 9 years old, born from consanguineous parents, were referred to the department of medical genetics at the National Institute of Health in Rabat. The diagnosis of MCPH was made, based on reduced head circumference without brain architecture abnormalities. The two patients were subject to the whole-exome sequencing, which allowed to diagnose a novel homozygous mutation c.1027C > T; p.Gln343* in exon 8 of WDR62, a gene already known to be related to MCPH. Sanger sequencing confirmed the segregation of the mutation in the family.ConclusionOur data expends the spectrum of mutations in WDR62 gene, proves the efficiency and cost-effectiveness of whole exome sequencing for the molecular diagnosis of genetically heterogeneous disorders such MCPH. Exome sequencing led to the rapid and cost-effective identification of a novel homozygous mutation in WDR62 gene, thereby facilitating genetic counseling.
Project description:Alport syndrome (AS) is a familial hereditary nephropathy which is characterized by molecular abnormalities in Collagen IV a345. As more gene mutations are discovered, it has been reported that autosomal recessive disease accounts for a smaller proportion (about 4%) of AS patients than previously recognized. We report here a novel mutation in COL4A4 in a Chinese family with autosomal recessive AS. Patient 1 was a 24-year-old Chinese man. He and his brother (patient 2) had a history of proteinuria and hematuria with renal dysfunction and sensorineural deafness. Pathologic findings were consistent with Alport syndrome, and genetic analysis revealed that both patients had two heterozygous mutations, c.1423 G>T (p.Gly475Cys) in EX21/CDS20 and c.735 G>A (p.Pro245Pro) in EX12/CDS11, and that each mutation originated from their mother or father who were carriers for one of these two mutations. Both patients showed similar results by laboratory examination and histopathologic assessment. Patient 1 received ACEI treatment and ran a stable clinical course, whereas patient 2 refused ACEI treatment and had progressive deterioration of renal function. This is the first report of a novel mutation in the collagen domain of COL4A4 gene. The results add to the spectrum of mutations in COL4A4 of Alport syndrome.
Project description:Autosomal recessive primary microcephaly (MCPH) is a clinically and genetically heterogeneous disorder. Patients with MCPH exhibit reduced occipito-frontal head circumference and non-progressive intellectual disability. To date, 17 genes have been known as an underlying cause of MCPH in humans. ASPM (abnormal spindle-like, microcephaly associated) is the most commonly mutated MCPH gene.Identify the genetic defect underlying MCPH in a Saudi family.A cross-sectional clinical genetic study of a Saudi family.Madinah Maternity and Children Hospital and Centre for Genetics and Inherited Diseases, Taibah University.A molecular analysis was carried out on DNA samples from 10 individuals of a Saudi family segregating MCPH. DNA was isolated from the peripheral blood of 10 individuals, including 2 patients, and whole exome sequencing was performed using the Nextera Rapid Capture kit and NextSeq500 instrument. VariantStudio was used to filter and prioritize variants.Detection of mutation in the ASPM gene in a family segregating autoso- mal recessive primary microcephaly.A novel homozygous splice-site variant (c.3742-1G > C) in the ASPM gene was identified. The variant is predicted to have an effect on splicing. Human Splice Finder, an in silico tool, predicted skipping of exon 16 due to this variant.Skipping of exon 16 may change the order and number of IQ motifs in the ASPM protein leading to typical MCPH phenotype.Single family study.
Project description:PurposeTo describe the clinical features, imaging characteristics, and genetic test results associated with a novel compound heterozygous mutation of the BEST1 gene in two siblings with autosomal recessive bestrophinopathy.MethodsTwo siblings underwent a complete ophthalmic examination, including dilated fundus examination, fundus photography, fundus autofluorescence imaging, spectral-domain optical coherence tomography, fluorescein angiography, electroretinography, and electrooculography. A clinical diagnosis of autosomal recessive bestrophinopathy was established based on ocular examination and multimodal retinal imaging. Subsequently, clinical exome sequencing consisting of a panel of 6670 genes was carried out to confirm the diagnosis and assess genetic alterations in the protein-coding region of the genome of the patients. The identified mutations were tested in the two affected siblings and one of their parents.ResultsTwo siblings (a 17-year-old female and a 15-year-old male) presented with reduced visual acuity and bilaterally symmetrical subretinal deposits of hyperautofluorescent materials in the posterior pole, which showed staining in the late phase of fluorescein angiogram. Spectral-domain optical coherence tomography demonstrated hyperreflective subretinal deposits and subretinal fluid accumulation. Both patients shared two mutations in the protein-coding region of the BEST1 gene, c.103G > A, p.(Glu35Lys) and c.313C > A, p.(Arg105Ser) (a novel disease-causing mutation). Sanger sequencing confirmed that the unaffected mother of the proband was carrying p.(Glu35Lys) variant in a heterozygous state.ConclusionsWe have identified and described the phenotype of a novel disease-causing mutation NM_004183.4:c.313C > A, p.(Arg105Ser) in a heterozygous state along with a previously reported mutation NM_004183.4:c.103G > A, p.(Glu35Lys) of the BEST1 gene in two related patients with autosomal recessive bestrophinopathy.
Project description:Mutations in the lipase member H (LIPH) gene cause autosomal recessive hypotrichosis with woolly hair. We report herein on five consanguineous families from Pakistan segregating hypotrichosis and woolly hair. Genetic investigation using polymorphic microsatellite markers revealed homozygosity for a region spanning the HYPT7 locus on chromosome 3 in affected individuals of all five families. Sequence analysis of the LIPH gene revealed a novel nonsense mutation (p.Arg260X) associated with hypotrichosis without woolly hair in one family. In the remaining four families we identified previously described mutations in a homozygous state in affected members. These findings extend the spectrum of known LIPH mutations in the Pakistani population.
Project description:Structure-function implication on a novel homozygous Trp250/Gly mutation of transglutaminase-1 (TGM1) observed in a patient of autosomal recessive congenital ichthyosis is invoked from a bioinformatics analysis. Structural consequences of this mutation are hypothesized in comparison to homologous enzyme human factor XIIIA accepted as valid in similar structural analysis and are projected as guidelines for future studies at an experimental level on TGM1 thus mutated.
Project description:Congenital recessive myotonia is a rare genetic disorder caused by mutations in CLCN1, which codes for the main skeletal muscle chloride channel ClC-1. More than 120 mutations have been found in this gene. The main feature of this disorder is muscle membrane hyperexcitability. Here, we report a 59-year male patient suffering from congenital myotonia. He had transient generalized myotonia, which started in early childhood. We analyzed CLCN1 sequence in this patient and other members of his family. We found a new missense mutation in CLCN1 gene (c.1886T>C, p.Leu629Pro). Co-segregation of this mutation with the disease was demonstrated by direct sequencing of the fragment in affected as well as unaffected members of this family. In addition, in silico analyses predicted that this nucleotide change would impair the protein function. Thus, this new nucleotide variation can be used for prenatal diagnosis in this family.