scholarly journals SLC22A4 Gene in Hereditary Non-syndromic Hearing Loss: Recurrence and Incomplete Penetrance of the p.C113Y Mutation in Northwest Africa

2021 ◽  
Vol 12 ◽  
Author(s):  
Chiara Chiereghin ◽  
Michela Robusto ◽  
Lucia Mauri ◽  
Paola Primignani ◽  
Pierangela Castorina ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Geographical Area ◽  
Missense Variant ◽  
African Population ◽  
Study Cohort ◽  
Incomplete Penetrance ◽  
The North ◽  
Northwest Africa ◽  
North African Population ◽  
Independent Replication

Inherited hearing loss is extremely heterogeneous both clinically and genetically. In addition, the spectrum of deafness-causing genetic variants differs greatly among geographical areas and ethnicities. The identification of the causal mutation in affected families allows early diagnosis, clinical follow-up, and genetic counseling. A large consanguineous family of Moroccan origin affected by autosomal recessive sensorineural hearing loss (ARSNHL) was subjected to genome-wide linkage analysis and exome sequencing. Exome-wide variant analysis and prioritization identified the SLC22A4 p.C113Y missense variant (rs768484124) as the most likely cause of ARSNHL in the family, falling within the unique significant (LOD score>3) linkage region on chromosome 5. Indeed, the same variant was previously reported in two Tunisian ARSNHL pedigrees. The variant is present in the homozygous state in all six affected individuals, but also in one normal-hearing sibling, suggesting incomplete penetrance. The mutation is absent in about 1,000 individuals from the Greater Middle East Variome study cohort, including individuals from the North African population, as well as in an additional seven deaf patients from the same geographical area, recruited and screened for mutations in the SLC22A4 gene. This study represents the first independent replication of the involvement of SLC22A4 in ARSNHL, highlighting the importance of the gene, and of the p.C113Y mutation, at least in the Northwest African population.

scholarly journals LRRK2 G2019S in the North African Population: A Review

2010 ◽  
Vol 63 (6) ◽  
pp. 321-325 ◽  
Author(s):  
Hani T.S. Benamer ◽  
Rajith de Silva
Keyword(s):  
African Population ◽  
North African ◽  
The North ◽  
North African Population

scholarly journals The Aurora Kinase C c.144delC mutation causes meiosis I arrest in men and is frequent in the North African population

2009 ◽  
Vol 18 (7) ◽  
pp. 1301-1309 ◽  
Author(s):  
K. Dieterich ◽  
R. Zouari ◽  
R. Harbuz ◽  
F. Vialard ◽  
D. Martinez ◽  
...  
Keyword(s):  
Aurora Kinase ◽  
African Population ◽  
North African ◽  
The North ◽  
Kinase C ◽  
North African Population ◽  
Meiosis I

Genetic diversity of the North African population revealed by the typing of SNPs in the DRD2/ANKK1 genomic region

Gene ◽  
2021 ◽  
Vol 777 ◽  
pp. 145466
Author(s):  
Souhir Mestiri ◽  
Sami Boussetta ◽  
Andrew J. Pakstis ◽  
Sarra Elkamel ◽  
Amel Ben Ammar Elgaaied ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genomic Region ◽  
African Population ◽  
North African ◽  
The North ◽  
North African Population

scholarly journals Identification and Characterization of the Most Common Genetic Variant Responsible for Acephalic Spermatozoa Syndrome in Men Originating from North Africa

2021 ◽  
Vol 22 (4) ◽  
pp. 2187
Author(s):  
Caroline Cazin ◽  
Yasmine Boumerdassi ◽  
Guillaume Martinez ◽  
Selima Fourati Ben Mustapha ◽  
Marjorie Whitfield ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
North Africa ◽  
Posterior Part ◽  
North African ◽  
The North ◽  
Transmission Electron ◽  
Variant Filtering ◽  
North African Population ◽  
Sperm Nuclei

Acephalic spermatozoa syndrome (ASS) is a rare but extremely severe type of teratozoospermia, defined by the presence of a majority of headless flagella and a minority of tail-less sperm heads in the ejaculate. Like the other severe monomorphic teratozoospermias, ASS has a strong genetic basis and is most often caused by bi-allelic variants in SUN5 (Sad1 and UNC84 domain-containing 5). Using whole exome sequencing (WES), we investigated a cohort of nine infertile subjects displaying ASS. These subjects were recruited in three centers located in France and Tunisia, but all originated from North Africa. Sperm from subjects carrying candidate genetic variants were subjected to immunofluorescence analysis and transmission electron microscopy. Moreover, fluorescent in situ hybridization (FISH) was performed on sperm nuclei to assess their chromosomal content. Variant filtering permitted us to identify the same SUN5 homozygous frameshift variant (c.211+1_211+2dup) in 7/9 individuals (78%). SUN5 encodes a protein localized on the posterior part of the nuclear envelope that is necessary for the attachment of the tail to the sperm head. Immunofluorescence assays performed on sperm cells from three mutated subjects revealed a total absence of SUN5, thus demonstrating the deleterious impact of the identified variant on protein expression. Transmission electron microscopy showed a conserved flagellar structure and a slightly decondensed chromatin. FISH did not highlight a higher rate of chromosome aneuploidy in spermatozoa from SUN5 patients compared to controls, indicating that intra-cytoplasmic sperm injection (ICSI) can be proposed for patients carrying the c.211+1_211+2dup variant. These results suggest that the identified SUN5 variant is the main cause of ASS in the North African population. Consequently, a simple and inexpensive genotyping of the 211+1_211+2dup variant could be beneficial for affected men of North African origin before resorting to more exhaustive genetic analyses.

scholarly journals Allelic Variants in Established Hypopituitarism Genes Expand Our Knowledge of the Phenotypic Spectrum

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1128
Author(s):  
Marilena Nakaguma ◽  
Nathalia Garcia Bianchi Pereira Ferreira ◽  
Anna Flavia Figueredo Benedetti ◽  
Mariana Cotarelli Madi ◽  
Juliana Moreira Silva ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Male Patient ◽  
Missense Variant ◽  
Hormone Deficiency ◽  
Pituitary Hormone ◽  
Incomplete Penetrance ◽  
Growth Hormone Gene ◽  
Posterior Lobe ◽  
Allelic Variants ◽  
Phenotypic Spectrum

We report four allelic variants (three novel) in three genes previously established as causal for hypopituitarism or related disorders. A novel homozygous variant in the growth hormone gene, GH1 c.171delT (p.Phe 57Leufs*43), was found in a male patient with severe isolated growth hormone deficiency (IGHD) born to consanguineous parents. A hemizygous SOX3 allelic variant (p.Met304Ile) was found in a male patient with IGHD and hypoplastic anterior pituitary. YASARA, a tool to evaluate protein stability, suggests that p.Met304Ile destabilizes the SOX3 protein (ΔΔG = 2.49 kcal/mol). A rare, heterozygous missense variant in the TALE homeobox protein gene, TGIF1 (c.268C>T:p.Arg90Cys) was found in a patient with combined pituitary hormone deficiency (CPHD), diabetes insipidus, and syndromic features of holoprosencephaly (HPE). This variant was previously reported in a patient with severe holoprosencephaly and shown to affect TGIF1 function. A novel heterozygous TGIF1 variant (c.82T>C:p.Ser28Pro) was identified in a patient with CPHD, pituitary aplasia and ectopic posterior lobe. Both TGIF1 variants have an autosomal dominant pattern of inheritance with incomplete penetrance. In conclusion, we have found allelic variants in three genes in hypopituitarism patients. We discuss these variants and associated patient phenotypes in relation to previously reported variants in these genes, expanding our knowledge of the phenotypic spectrum in patient populations.

scholarly journals A biallelic variant in CLRN2 causes non-syndromic hearing loss in humans

2021 ◽  
Author(s):  
Barbara Vona ◽  
Neda Mazaheri ◽  
Sheng-Jia Lin ◽  
Lucy A. Dunbar ◽  
Reza Maroofian ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Amino Acid ◽  
Rna Splicing ◽  
Stop Codon ◽  
Missense Variant ◽  
Homozygosity Mapping ◽  
Deafness Gene ◽  
Expression Studies ◽  
Hearing Function

AbstractDeafness, the most frequent sensory deficit in humans, is extremely heterogeneous with hundreds of genes involved. Clinical and genetic analyses of an extended consanguineous family with pre-lingual, moderate-to-profound autosomal recessive sensorineural hearing loss, allowed us to identify CLRN2, encoding a tetraspan protein, as a new deafness gene. Homozygosity mapping followed by exome sequencing identified a 14.96 Mb locus on chromosome 4p15.32p15.1 containing a likely pathogenic missense variant in CLRN2 (c.494C > A, NM_001079827.2) segregating with the disease. Using in vitro RNA splicing analysis, we show that the CLRN2 c.494C > A variant leads to two events: (1) the substitution of a highly conserved threonine (uncharged amino acid) to lysine (charged amino acid) at position 165, p.(Thr165Lys), and (2) aberrant splicing, with the retention of intron 2 resulting in a stop codon after 26 additional amino acids, p.(Gly146Lysfs*26). Expression studies and phenotyping of newly produced zebrafish and mouse models deficient for clarin 2 further confirm that clarin 2, expressed in the inner ear hair cells, is essential for normal organization and maintenance of the auditory hair bundles, and for hearing function. Together, our findings identify CLRN2 as a new deafness gene, which will impact future diagnosis and treatment for deaf patients.

scholarly journals A combined in silico, in vitro and clinical approach to characterise novel pathogenic missense variants in PRPF31 in retinitis pigmentosa

2018 ◽  
Author(s):  
Gabrielle Wheway ◽  
Liliya Nazlamova ◽  
Nervine Meshad ◽  
Samantha Hunt ◽  
Nicola Jackson ◽  
...  
Keyword(s):  
Retinitis Pigmentosa ◽  
In Silico ◽  
Autosomal Dominant ◽  
Missense Variant ◽  
Incomplete Penetrance ◽  
Clinical Approach ◽  
Loss Of Function ◽  
Autosomal Dominant Retinitis Pigmentosa ◽  
Missense Variants

AbstractAt least six different proteins of the spliceosome, including PRPF3, PRPF4, PRPF6, PRPF8, PRPF31 and SNRNP200, are mutated in autosomal dominant retinitis pigmentosa (adRP). These proteins have recently been shown to localise to the base of the connecting cilium of the retinal photoreceptor cells, elucidating this form of RP as a retinal ciliopathy. In the case of loss-of-function variants in these genes, pathogenicity can easily be ascribed. In the case of missense variants, this is more challenging. Furthermore, the exact molecular mechanism of disease in this form of RP remains poorly understood.In this paper we take advantage of the recently published cryo EM-resolved structure of the entire human spliceosome, to predict the effect of a novel missense variant in one component of the spliceosome; PRPF31, found in a patient attending the genetics eye clinic at Bristol Eye Hospital. Monoallelic variants in PRPF31 are a common cause of autosomal dominant retinitis pigmentosa (adRP) with incomplete penetrance. We use in vitro studies to confirm pathogenicity of this novel variant PRPF31 c.341T>A, p.Ile114Asn.This work demonstrates how in silico modelling of structural effects of missense variants on cryo-EM resolved protein complexes can contribute to predicting pathogenicity of novel variants, in combination with in vitro and clinical studies. It is currently a considerable challenge to assign pathogenic status to missense variants in these proteins.

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