RESUMEN
A reference genotyping laboratory was established in 2000 at Queen's University, Kingston, to provide genetic testing for Hemophilia A (HA) and B (HB) and create a Canadian mutation database. Canadian hemophilia treatment centers and genetics clinics provided DNA and clinical information from November 2000 to March 2011. The factor VIII (F8) gene was analyzed in 1,177 patients (47% of HA population) and 787 female family members and the factor IX (F9) gene in 267 patients (47% of HB population) and 123 female family members, using Southern Blot, PCR, conformation sensitive gel electrophoresis, and/or direct sequencing. The mutation detection rates for HA and HB were 91% and 94%, respectively. 380 different F8 mutations were identified: inversions of intron 22 and intron 1, 229 missense, 45 nonsense, eight deletions, 70 frameshifts, 25 splice site, and one compound mutation with a splice site and intron 1 inversion. Of these mutations, 228 were novel to the Hemophilia A Database (HADB, http://hadb.org.uk/). A total 125 different F9 mutations were identified: 80 missense, 12 frameshift, 12 splice site, nine nonsense and seven promoter mutations, three large deletions, and two compound mutations with both missense and nonsense changes. Of these mutations, 36 were novel to the International Haemophilia B Mutation database (http://www.kcl.ac.uk/ip/petergreen/haemBdatabase.html). The Canadian F8 and F9 mutation database reflects the allelic heterogeneity of HA and HB, and is similar to previously described populations. This report represents the largest and longest duration experience of a national hemophilia genotyping program documented, to date.
Asunto(s)
Bases de Datos Genéticas , Factor IX/genética , Factor VIII/genética , Hemofilia A/genética , Hemofilia B/genética , Mutación , Canadá/epidemiología , Análisis Mutacional de ADN , Exones/genética , Femenino , Frecuencia de los Genes , Tamización de Portadores Genéticos , Pruebas Genéticas , Hemofilia A/epidemiología , Hemofilia B/epidemiología , Humanos , Intrones/genética , Masculino , Fenotipo , Diagnóstico Prenatal , Sitios de Empalme de ARN , Estudios Retrospectivos , Análisis de Secuencia de ADN , Inversión de Secuencia , Terminología como Asunto , Enfermedad de von Willebrand Tipo 2/epidemiología , Enfermedad de von Willebrand Tipo 2/genéticaRESUMEN
<p><b>OBJECTIVE</b>To establish a simple, rapid and easy method for screening the gene mutation in hemophilia A, which was further applied to a direct diagnosis and carrier detection at gene level.</p><p><b>METHODS</b>Twenty-four clinically diagnosed hemophilia pedigrees, including all the hemophilia patients and female members, were tested for the introns 22 and 1 in factor VIII gene by using inversion polymerase chain reaction (PCR) and regular PCR techniques. All the 26 exons of factor VIII gene were consecutively screened in the 17 patients manifesting non-inverted sequences in intron 22 by using PCR, subsequently all the 37 amplicons resulted from 26 exons were analyzed by conformation sensitive gel electrophoresis (CSGE), finally the mutated exons were subjected to sequencing verification. According to the mutation results, mothers and twin sisters of the hemophilia probands were tested by CSGE or subjected to nucleotide sequencing directly, to ascertain if those individuals had the same mutation or were the carriers of disease-causing gene.</p><p><b>RESULTS</b>Intron 22 inversion was detected in 7 hemophilia probands out of 24 hemophilia pedigrees, intron 1 inversion was not detected in these pedigrees. Single-base mutations distributed in different exons of factor VIII gene were detected in 13 pedigrees with family history and 3 sporadic pedigrees, diagnosed as non-inverted 22 intron patients. By comprehensive usage of PCR-CSGE and nucleotide sequencing, the positive rate and the diagnosable rate of gene diagnosis or carrier detection in the 24 hemophilia pedigrees was 94.12% and 100% respectively.</p><p><b>CONCLUSION</b>PCR-CSGE is a highly sensitive and special assay for detecting single base mutation. By integrated utilization of introns 22 and 1 of factor VIII gene detection and PCR-CSGE genotyping, combining with nucleotide sequencing, a direct diagnosis of all hemophilia pedigrees be could nearly make at gene level, including the sporadic families. This method might be used to screen new mutation theoretically and ascertain the mutation type. It is a simple, rapid and low-cost method, possessing unique advantages in direct diagnosis of hemophilia A and carrier screening. It should have important application value in hemophilia diagnosis.</p>