Asunto(s)
Mutación , Porfiria Eritropoyética/diagnóstico , Porfiria Eritropoyética/genética , Uroporfirinógeno III Sintetasa/genética , Trasplante de Médula Ósea , Análisis Mutacional de ADN , Femenino , Hepatomegalia , Humanos , Lactante , Fenotipo , Porfiria Eritropoyética/terapia , Esplenomegalia , Tailandia , Trasplante Homólogo , Resultado del TratamientoRESUMEN
A reliable method for determination of carrier status and genetic counselling is required for effective control of haemophilia. Linkage analysis is currently the most widely used method for this purpose; however, in cases where there is no prior family history and/or unavailability of informative polymorphic markers it is less applicable. Detection of a mutation characterized in each family may be an alternative method for determination of the carrier status. In this study, linkage analysis using four polymorphic DNA markers, and direct mutation analysis were compared to determine the carrier status in six unrelated Thai haemophilia A families, two with a family history and four without. In the two families with a family history of haemophilia A, the carrier and noncarrier statuses could readily be determined in eight females by either linkage or direct mutation analysis. In the four families without a family history, the polymorphic DNA markers for linkage analysis were informative in two families and uninformative in the other two. The carrier status could be excluded in all four female siblings of the patients in the former. However, the specific FVIII gene mutation was not observed in the mother of one patient, who should have carried the mutation. In the remaining two families with uninformative polymorphic DNA markers, the carrier and noncarrier statuses of four female members could only be determined by direct mutation analysis. Therefore, direct mutation analysis could circumvent the limitations of linkage analysis in the determination of haemophilia A carrier status in families without a previous history or informative polymorphic markers.
Asunto(s)
Hemofilia A/genética , Análisis Mutacional de ADN , Femenino , Heterocigoto , Humanos , Masculino , LinajeRESUMEN
Hemophilia A is a common X-linked bleeding disorder caused by mutations in the coagulation factor VIII gene. The entire coding and essential sequences of the factor VIII gene were generated by a combination of genomic DNA amplification and long reverse transcription-polymerase chain reaction (long RT-PCR) using factor VIII transcripts prepared from lymphocytes. Mutations were then screened by non-radioactive single strand conformation polymorphism (SSCP) analysis and characterized by DNA sequencing. We have identified six potentially pathogenic mutations in the factor VIII gene in Thai hemophilia A patients, including two nonsense mutations (R-5X and R1966X), three missense mutations (D542Y, G1850V, and G2325C), and a 4-bp insertion (ACTA) at codon 2245. Three of these mutations (D542Y, G2325C, and 4-bp insertion) have never been previously reported, and the ins2245 is the first example of such insertion probably causing factor VIII elongation. R1966X, D542Y, G1850V, and 4-bp insertion were associated with a severe hemophiliac phenotype whereas R-5X and G2325C were observed in moderately affected patients. Mutations in the factor VIII gene in Thai hemophilia A patients are likely to be heterogeneous. This study represents the first attempt to further the understanding of the molecular basis of hemophilia A in Thai.
Asunto(s)
Factor VIII/genética , Hemofilia A/genética , Secuencia de Aminoácidos , Animales , Bovinos , Ceruloplasmina/genética , Factor V/genética , Femenino , Humanos , Masculino , Ratones , Datos de Secuencia Molecular , Mutación , Reacción en Cadena de la Polimerasa , Polimorfismo Conformacional Retorcido-Simple , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Alineación de Secuencia , Porcinos , TailandiaRESUMEN
Among the eight families of Anopheles willmori derived from individual wild-caught females collected from Chiangmai Province (northern Thailand) and examined, four isofemale lines showed variation in the X chromosome, including the normal X1 and three aberrant types (X3, X4 and XL). It is postulated that these different types of X chromosomes could have arisen as a result of spontaneous chromosomal rearrangements involving tandem translocation and paracentric inversion followed by acquisition of constitutive heterochromatin. Such rare events of chromosomal changes have become established in the natural population of An. willmori in northern Thailand.