Assuntos
Proteínas do Citoesqueleto/genética , Proteínas de Membrana/genética , Monoéster Fosfórico Hidrolases/genética , Neoplasias Cutâneas/etiologia , Neoplasias Cutâneas/genética , Transativadores , Proteínas Supressoras de Tumor/genética , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , PTEN Fosfo-Hidrolase , Receptores Patched , Receptor Patched-1 , Linhagem , Receptores de Superfície Celular , Síndrome , beta CateninaRESUMO
Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder characterized by oculocutaneous albinism and a storage pool deficiency due to an absence of platelet dense bodies. Lysosomal ceroid lipofuscinosis, pulmonary fibrosis and granulomatous colitis are occasional manifestations of the disease. HPS occurs with a frequency of one in 1800 in north-west Puerto Rico due to a founder effect. Several non-Puerto Rican patients also have mutations in HPS1, which produces a protein of unknown function. Another gene, ADTB3A, causes HPS in the pearl mouse and in two brothers with HPS-2 (refs. 11,12). ADTB3A encodes a coat protein involved in vesicle formation, implicating HPS as a disorder of membrane trafficking. We sought to identify other HPS-causing genes. Using homozygosity mapping on pooled DNA of 6 families from central Puerto Rico, we localized a new HPS susceptibility gene to a 1.6-cM interval on chromosome 3q24. The gene, HPS3, has 17 exons, and a putative 113.7-kD product expected to reveal how new vesicles form in specialized cells. The homozygous, disease-causing mutation is a large deletion and represents the second example of a founder mutation causing HPS on the small island of Puerto Rico. We also present an allele-specific assay for diagnosing individuals heterozygous or homozygous for this mutation.
Assuntos
Proteínas de Transporte/genética , Cromossomos Humanos Par 3/genética , Síndrome de Hermanski-Pudlak/genética , Alelos , Sequência de Aminoácidos , Northern Blotting , Análise Mutacional de DNA , Feminino , Efeito Fundador , Triagem de Portadores Genéticos , Predisposição Genética para Doença , Genótipo , Síndrome de Hermanski-Pudlak/epidemiologia , Homozigoto , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Dados de Sequência Molecular , Mutação , Especificidade de Órgãos , Linhagem , Fenótipo , Mapeamento Físico do Cromossomo , Porto Rico/epidemiologia , Deleção de SequênciaRESUMO
Lamellar ichthyosis (LI, OMIM no. 242300) is a severe autosomal recessive genodermatosis with an estimated prevalence of 1:200,000. LI represents one end of the spectrum of congenital recessive ichthyosis (CRI). Mutations in the gene for transglutaminase-1 (TGM1) are responsible for many cases of LI and occur throughout the coding sequence of the gene. Our analyses of patients with CRI revealed a common TGM1 mutation involving loss of the intron 5 splice acceptor site leading to alternative splicing of the message. We found families in which the splice acceptor site mutation was homozygous, and families where the patients were compound heterozygotes for the splice acceptor site mutation and another TGM1 mutation. A mutation at this same site occurs in the majority of Norwegian patients as a founder effect. In our ethnically diverse patient population, none of whom have known Norwegian ancestry, haplotype analysis of the TGM1 chromosomal region also suggested the existence of a founder effect. Comparison of the common haplotype in our data with the Norwegian data showed that 2/7 of our splice acceptor site mutation chromosomes had the full reported Norwegian haplotype, and the remaining five chromosomes exhibited recombination at the most distal marker studied. History, family origins, and haplotype analysis suggested that the mutation originally arose on a German background and was introduced into Norway around 800-1000 AD. We also found a limited correlation between genotype and phenotype in our study, with the four homozygous patients having less severe disease than many of the heterozygotes, and no patient with a splice acceptor site mutation having erythroderma or a congenital ichthyosiform erythroderma phenotype.
Assuntos
Ictiose/genética , Mutação , Adolescente , Adulto , Sequência de Bases , Criança , Pré-Escolar , Análise Mutacional de DNA , Primers do DNA/genética , Feminino , Efeito Fundador , Genes Recessivos , Alemanha , Haplótipos , Humanos , Ictiose/patologia , Masculino , Pessoa de Meia-Idade , Noruega , Linhagem , Splicing de RNA/genética , Estados UnidosRESUMO
The need continues to grow for mutation identification in genetic disease in both research and clinical settings. We have developed a rapid nonradioactive bidirectional dideoxy fingerprint mutation screening procedure that is performed using an automated DNA analyzer. This technique features standardized primers and easily interpreted results from separate, but simultaneously collected, images for coding and noncoding strands. Another advantage is simplified mutation verification by sequencing using the same amplified DNA templates and also application to large multi-exon genes. We demonstrate the efficiency and reproducibility of the method in which we screen a DNA fragment encompassing exon 5 of the PTCH gene (in which mutations cause Gorlin Syndrome) in a panel of 22 patients.