RESUMO
We present the molecular genetic analysis of an infantile-onset Sandhoff disease patient. Genomic DNA amplification, heteroduplex analysis, cloning and sequencing revealed a 4-bp deletion in exon 4 (497 DeltaAGTT). The result is a frameshift mutation that leads to a stop codon in exon 5. This mutation is associated with a dramatic decrease of HEXB mRNA levels.
Assuntos
Códon de Terminação , Mutação da Fase de Leitura , Doença de Sandhoff/genética , Deleção de Sequência , beta-N-Acetil-Hexosaminidases/genética , Sequência de Bases , Gangliosidoses GM2/genética , Gangliosidoses GM2/metabolismo , Hexosaminidase B , Humanos , Lactente , Masculino , Reação em Cadeia da Polimerase , RNA Mensageiro/análiseRESUMO
Two novel frameshift adrenoleukodystrophy mutations in two families were identified: a complex dinucleotide deletion/tetranucleotide insertion at 1116 TC-->GAGA (codon 244 [serine]) and an AG deletion at nucleotide 1462 (codon 359 [glutamic acid]). Both mutations are predicted to cause premature termination of protein synthesis. The patients were affected by childhood cerebral adrenoleukodystrophy and by adrenomyeloneuropathy with mild Addison disease, respectively.
Assuntos
Adrenoleucodistrofia/genética , Mutação da Fase de Leitura/fisiologia , Adrenoleucodistrofia/fisiopatologia , Adrenoleucodistrofia/psicologia , Adulto , Criança , Éxons , Humanos , Itália , Masculino , Linhagem , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
The authors present two new missense mutations in exon 1 of the adrenoleukodystrophy (ALD) gene. The first, a C813T transition, results in the substitution Pro143 Ser in the third putative transmembrane domain of the adrenoleukodystrophy protein (ALDP) in an adult onset case. The second, a de novo C709T transition, results in a substitution Ser 108 Leu between the second and the third putative transmembrane segments, in a childhood case.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Adrenoleucodistrofia/genética , Proteínas de Membrana/genética , Mutação de Sentido Incorreto , Membro 1 da Subfamília D de Transportadores de Cassetes de Ligação de ATP , Adulto , Criança , Feminino , Humanos , Itália , Leucina/genética , Masculino , Linhagem , Prolina/genética , Serina/genéticaRESUMO
Metachromatic leukodystrophy (MLD) is an autosomal recessive storage disease caused by deficiency of the lysosomal enzyme, arylsulfatase A. Two common mutations causing MLD have been characterized and correlations between phenotype and genotype have been established. A third common mutation, T799G, has also been identified in European MLD patients, and is associated with the late-onset forms of the disease. We report the molecular analysis of two Italian MLD patients, with juvenile and adult onset of the disease, respectively, who carried the T799G mutation in compound heterozygosity with different null mutations. A novel rapid mutation detection method is demonstrated for patient screening. One patient has a novel mutation, a T553C [corrected] transition that results in the substitution of Pro for Leu at codon 135, and produces no enzymatic activity in transfection experiments.
Assuntos
Substituição de Aminoácidos/genética , Leucodistrofia Metacromática/enzimologia , Leucodistrofia Metacromática/genética , Mutação , Adulto , Animais , Células Cultivadas , Cerebrosídeo Sulfatase/genética , Criança , Cricetinae , Feminino , Fibroblastos , Heterozigoto , Humanos , Masculino , FenótipoAssuntos
Processamento Alternativo/genética , Mutação/genética , Doença de Sandhoff/genética , Northern Blotting , DNA/sangue , DNA/isolamento & purificação , Evolução Fatal , Feminino , Humanos , Lactente , Linhagem , RNA/sangue , RNA/isolamento & purificação , Doença de Sandhoff/enzimologia , beta-N-Acetil-Hexosaminidases/genéticaRESUMO
A novel mutation, a C-->T transition at nucleotide 455 of the coding sequence of the ARSA gene, was found in a control individual during the search for metachromatic leukodystrophy mutations. Its distribution in three different populations was examined. The frequency of the T allele was 0.058, 0.025 and 0.033, in Italian, German and Greek populations, respectively. The mutation results in no amino acid substitution and can be identified as it creates a a polymorphic site for the restriction endonuclease N/aIII.
Assuntos
Cerebrosídeo Sulfatase/genética , Mutação , Polimorfismo Genético , Frequência do Gene , Genética Populacional , Alemanha , Grécia , Humanos , Itália , Leucodistrofia Metacromática/genéticaRESUMO
beta-Hexosaminidase gene mutations were analyzed in two adult-onset Sandhoff disease Italian patients by PCR analysis of a common known mutation (delta 5') and by heteroduplex analysis of genomic and RT-PCR DNA fragments, covering the whole gene. The patients' genotypes were delta 5'/C1214%, and G890A/C1214T, respectively. As mutation C1214T (Pro405Leu) is also present in the other two late-onset cases so far described, we suggest that C1214T is a common mutation in this type of Sandhoff disease. Mutation G890A (Cys297Tyr) is a novel mutation which presumably causes altered processing of the pro beta chain.