@article {485, title = {A variant in LMX1A causes autosomal recessive severe-to-profound hearing impairment.}, journal = {Hum Genet}, volume = {137}, year = {2018}, month = {2018 Jul}, pages = {471-478}, abstract = {

Hereditary hearing impairment is a common sensory disorder that is genetically and phenotypically heterogeneous. In this study, we used a homozygosity mapping and exome sequencing strategy to study a consanguineous Pakistani family with autosomal recessive severe-to-profound hearing impairment. This led to the identification of a missense variant (p.Ile369Thr) in the LMX1A gene affecting a conserved residue in the C-terminus of the protein, which was predicted damaging by an in silico bioinformatics analysis. The p.Ile369Thr variant disrupts several C-terminal and homeodomain residue interactions, including an interaction with homeodomain residue p.Val241 that was previously found to be involved in autosomal dominant progressive HI. LIM-homeodomain factor Lmx1a is expressed in the inner ear through development, shows a progressive restriction to non-sensory epithelia, and is important in the separation of the sensory and non-sensory domains in the inner ear. Homozygous Lmx1a mutant mice (Dreher) are deaf with dysmorphic ears with an abnormal morphogenesis and fused and misshapen sensory organs; however, computed tomography performed on a hearing-impaired family member did not reveal any cochleovestibular malformations. Our results suggest that LMX1A is involved in both human autosomal recessive and dominant sensorineural hearing impairment.

}, keywords = {Adolescent, Adult, Animals, Child, Disease Models, Animal, Ear, Inner, Female, Genes, Dominant, Genes, Recessive, Hearing Loss, Hearing Loss, Sensorineural, Homozygote, Humans, LIM-Homeodomain Proteins, Male, Mice, Mutation, Missense, Pedigree, Transcription Factors, Whole Exome Sequencing}, issn = {1432-1203}, doi = {10.1007/s00439-018-1899-7}, author = {Schrauwen, Isabelle and Chakchouk, Imen and Liaqat, Khurram and Jan, Abid and Nasir, Abdul and Hussain, Shabir and Nickerson, Deborah A and Bamshad, Michael J and Ullah, Asmat and Ahmad, Wasim and Leal, Suzanne M} } @article {632, title = {Sequence variants in nine different genes underlying rare skin disorders in 10 consanguineous families.}, journal = {Int J Dermatol}, volume = {56}, year = {2017}, month = {2017 Dec}, pages = {1406-1413}, abstract = {

BACKGROUND: Genodermatoses represent genetic anomalies of skin tissues including hair follicles, sebaceous glands, eccrine glands, nails, and teeth. Ten consanguineous families segregating various genodermatosis phenotypes were investigated in the present study.

METHODS: Homozygosity mapping, exome, and Sanger sequencing were employed to search for the disease-causing variants in the 10 families.

RESULTS: Exome sequencing identified seven homozygous sequence variants in different families, including: c.27delT in FERMT1; c.836delA in ABHD5; c.2453C>T in ERCC5; c.5314C>T in COL7A1; c.1630C>T in ALOXE3; c.502C>T in PPOX; and c.10G>T in ALDH3A2. Sanger sequencing revealed three homozygous variants: c.1718~+~2A>G in FERMT1; c.10459A>T in FLG; and c.92delT in the KRT14 genes as the underlying genetic cause of skin phenotypes.

CONCLUSION: This study supports the use of exome sequencing as a powerful, efficient tool for identifying genes that underlie rare monogenic skin disorders.

}, keywords = {1-Acylglycerol-3-Phosphate O-Acyltransferase, Aldehyde Oxidoreductases, Blister, Collagen Type VII, Consanguinity, DNA Mutational Analysis, DNA-Binding Proteins, Endonucleases, Epidermolysis Bullosa, Epidermolysis Bullosa Dystrophica, Epidermolysis Bullosa Simplex, Exome, Female, Flavoproteins, Homozygote, Humans, Ichthyosiform Erythroderma, Congenital, Ichthyosis Vulgaris, Ichthyosis, Lamellar, INDEL Mutation, Intermediate Filament Proteins, Keratin-14, Lipid Metabolism, Inborn Errors, Lipoxygenase, Male, Membrane Proteins, Mitochondrial Proteins, Muscular Diseases, Neoplasm Proteins, Nuclear Proteins, Pedigree, Periodontal Diseases, Phenotype, Photosensitivity Disorders, Porphyria, Variegate, Protoporphyrinogen Oxidase, Rare Diseases, Sjogren-Larsson Syndrome, Skin Diseases, Genetic, Transcription Factors, Xeroderma Pigmentosum}, issn = {1365-4632}, doi = {10.1111/ijd.13778}, author = {Shah, Khadim and Mehmood, Sabba and Jan, Abid and Abbe, Izoduwa and Hussain Ali, Raja and Khan, Anwar and Chishti, Muhammad S and Lee, Kwanghyuk and Ahmad, Farooq and Ansar, Muhammad and Shahzad, Shaheen and Nickerson, Deborah A and Bamshad, Michael J and Coucke, Paul J and Santos-Cortez, Regie L P and Spritz, Richard A and Leal, Suzanne M and Ahmad, Wasim} } @article {100, title = {Expansion of the spectrum of ITGB6-related disorders to adolescent alopecia, dentogingival abnormalities and intellectual disability.}, journal = {Eur J Hum Genet}, volume = {24}, year = {2016}, month = {2016 08}, pages = {1223-7}, abstract = {

Alopecia with mental retardation (APMR) is a very rare disorder. In this study, we report on a consanguineous Pakistani family (AP91) with mild-to-moderate intellectual disability, adolescent alopecia and dentogingival abnormalities. Using homozygosity mapping, linkage analysis and exome sequencing, we identified a novel rare missense variant c.898G>A (p.(Glu300Lys)) in ITGB6, which co-segregates with the phenotype within the family and is predicted to be deleterious. Structural modeling shows that Glu300 lies in the β-propeller domain, and is surrounded by several residues that are important for heterodimerization with α integrin. Previous studies showed that ITGB6 variants can cause amelogenesis imperfecta in humans, but patients from family AP91 who are homozygous for the c.898G>A variant present with neurological and dermatological features, indicating a role for ITGB6 beyond enamel formation. Our study demonstrates that a rare deleterious variant within ITGB6 causes not only dentogingival anomalies but also intellectual disability and alopecia.

}, keywords = {Adolescent, Adult, Alopecia, Child, Female, Humans, Integrin beta Chains, Intellectual Disability, Male, Mutation, Missense, Pedigree, Phenotype, Protein Domains, Syndrome, Tooth Abnormalities}, issn = {1476-5438}, doi = {10.1038/ejhg.2015.260}, author = {Ansar, Muhammad and Jan, Abid and Santos-Cortez, Regie Lyn P and Wang, Xin and Suliman, Muhammad and Acharya, Anushree and Habib, Rabia and Abbe, Izoduwa and Ali, Ghazanfar and Lee, Kwanghyuk and Smith, Joshua D and Nickerson, Deborah A and Shendure, Jay and Bamshad, Michael J and Ahmad, Wasim and Leal, Suzanne M} } @article {204, title = {Challenges and solutions for gene identification in the presence of familial locus heterogeneity.}, journal = {Eur J Hum Genet}, volume = {23}, year = {2015}, month = {2015 Sep}, pages = {1207-15}, abstract = {

Next-generation sequencing (NGS) of exomes and genomes has accelerated the identification of genes involved in Mendelian phenotypes. However, many NGS studies fall short of identifying causal variants, with estimates for success rates as low as 25\% for uncovering the pathological variant underlying disease etiology. An important reason for such failures is familial locus heterogeneity, where within a single pedigree causal variants in two or more genes underlie Mendelian trait etiology. As examples of intra- and inter-sibship familial locus heterogeneity, we present 10 consanguineous Pakistani families segregating hearing impairment due to homozygous variants in two different hearing impairment genes and a European-American pedigree in which hearing impairment is caused by four variants in three different genes. We have identified 41 additional pedigrees with syndromic and nonsyndromic hearing impairment for which a single previously reported hearing impairment gene has been identified but only segregates with the phenotype in a subset of affected pedigree members. We estimate that locus heterogeneity occurs in 15.3\% (95\% confidence interval: 11.9\%, 19.9\%) of the families in our collection. We demonstrate novel approaches to apply linkage analysis and homozygosity mapping (for autosomal recessive consanguineous pedigrees), which can be used to detect locus heterogeneity using either NGS or SNP array data. Results from linkage analysis and homozygosity mapping can also be used to group sibships or individuals most likely to be segregating the same causal variants and thereby increase the success rate of gene identification.

}, keywords = {Asian Continental Ancestry Group, Calcium-Binding Proteins, Chromosome Mapping, Connexin 26, Connexins, Consanguinity, European Continental Ancestry Group, Female, Genes, Recessive, Genetic Heterogeneity, Genetic Linkage, Genetic Loci, Genetic Predisposition to Disease, Genome, Human, Genotype, Hearing Loss, Hepatocyte Growth Factor, High-Throughput Nucleotide Sequencing, Homozygote, Humans, Male, Membrane Transport Proteins, Mutation, Pedigree, Phenotype, Sulfate Transporters}, issn = {1476-5438}, doi = {10.1038/ejhg.2014.266}, author = {Rehman, Atteeq U and Santos-Cortez, Regie Lyn P and Drummond, Meghan C and Shahzad, Mohsin and Lee, Kwanghyuk and Morell, Robert J and Ansar, Muhammad and Jan, Abid and Wang, Xin and Aziz, Abdul and Riazuddin, Saima and Smith, Joshua D and Wang, Gao T and Ahmed, Zubair M and Gul, Khitab and Shearer, A Eliot and Smith, Richard J H and Shendure, Jay and Bamshad, Michael J and Nickerson, Deborah A and Hinnant, John and Khan, Shaheen N and Fisher, Rachel A and Ahmad, Wasim and Friderici, Karen H and Riazuddin, Sheikh and Friedman, Thomas B and Wilch, Ellen S and Leal, Suzanne M} }