TaqI digestion of PCR product increases the informativity of St14 VNTR for the diagnosis of hemophilia A.

Recently, a pair of PCR primers have been described that make it possible to amplify a highly polymorphic VNTR locus DX552 (St14). PCR products range in size from approximately 650 to 3000 bp. Ninety X chromosomes from unrelated Caucasian subjects were investigated. Digestion of the PCR products with TaqI revealed the presence of a polymorphic TaqI restriction site within the product 200 bp from the end. This restriction site is present on 60% and absent on 40% of all alleles, but the absence is confined solely to the alleles 1690 bp (39%) and 2100 bp (1%). Thus, there is a strong allelic association between the most frequent 1690 bp allele and the absence of the TaqI restriction site. Determination of this polymorphisms within the St14 VNTR region increases the expected heterozygosity at the DXS52 locus from 72% to 80%. This increases the fraction of hemophilia A families where this marker is informative for indirect prenatal diagnosis and carrier identification.

[Molecular genetic analysis of deletions in the Duchenne and Becker types of progressive muscular dystrophy]. / Molekulárno-genetická analýza delécií pri progresívych svalových dystrofiách typu Duchenne a Becker.

Methods of molecular genetics (Southern's hybridization and DNA amplification by the PCR method) were used to search the DNA of patients suffering from the Duchenne (DMD) and the Becker (BMD) type of progressive muscular dystrophy for deletions in the dystrophin gene. The series consisted of 29 patients with DMD and 2 patients with BMD. As hybridization probes cloned cDNA sections were used designated as CF56a, CF56b, 1-2a, 2b-3, 4-5a, 5b-7 and 8. With the PCR methods means for exons 8, 19, 45 and 48 were used. No deletion was found in either of the BMD patients. In 13 (44.8%) of the 29 DMD patients deletion with at least one cDNA probe was found. Most deletions were detected with the probes 8 (46.2%) and 1-2a (30.8%). The high proportion of deletions in the etiology of DMD/BMD has both a high differential diagnostic value and allows to make direct prenatal diagnosis as well as to determine transmission in these families with subsequent elimination of the risk of diagnostic error resulting from recombination in DNA diagnosis by means of binding. (Tab. 1, Fig. 2, Ref. 20.)

[Identification of a de novo mutation in a factor FVIII:C gene in a family requesting prenatal diagnosis of hemophilia A]. / Identifikácia de novo mutácie v géne pre faktor FVIII:C v rodine pozadujúcej prenatálnu diagnostiku hemofílie A.

Hemophilia is caused by wide spectrum of different mutations in the F8C gene which made the direct DNA diagnosis of the diseases not the case of choice. Indirect DNA diagnosis by means of linked restriction fragment length polymorphisms (RFLPs) provides the alternative. Using this method authors identified de novo mutation in a family requiring prenatal diagnosis of hemophilia A. This de novo mutation arose during the spermatogenesis of the proband's father. Attempts to characterize the mutation on the molecular level are presented. (Ref. 15, Fig. 1.).

Frequency and distribution of deletions in dystrophin gene in Duchenne muscular dystrophy patients from an east-European Slavonic population.

In 32 unrelated DMD patients originating from Slovakia (Czechoslovakia), screening for deletions in the dystrophin gene was performed with cDNA probes Cf56a, Cf56b, 1-2a, 2b-3 4-5a, 5b-7, and 8. In 14 out of 32 DMD patients (43.75 per cent), a deletion extending from one to three adjacent probes was observed. The highest proportion of deletions was found with probes 8 and 1-2a (50 and 28.6 per cent of all deletions, respectively). All these proportions are similar to those found in other populations of European origin.