HGM2002 Poster Abstracts: 7. Medical Genomics
POSTER NO: 344
Prenatal diagnosis of SMA and DMD in Moldova
Victoria Sacara, P. Stratulat
Introduction: Spinal muscular atrophy (SMA) has been classified into three clinical forms. This clinical impression has been borne out by the mapping of all forms of spinal muscular atrophy to one small region of chromosome 5. In 99% of patients who had this disorder, a mutation was found in a gene called survival motor neuron (SMN). The dystrophinopathies, Duchenne and Becker muscular dystrophy (D/BMD), is an X-linked recessive disorder. Assigned to Xp21.1, the dystrophin gene is one of the largest known so far in humans. Materials and methods: 105 families with increased risk of DMD, 20 families with SMA families appearance in offspring medico-genetic counselling at the National Centre of Medical Genetics. DNA preparations were made from peripheral blood samples by routine methods and used for conventional PCR, MPCR, RFLP. The chorion villus samples (CVS) were taken by the transabdominal route under ultrasonic guidance at an average gestational age of 8-10 weeks. Transabdominal amniocentesis was performed between 18-22 weeks of gestation. Results: 76% of D/BMD patients were proved to be carriers of dystrophin deletion. RFLP-analysis (pERT87-8/TaqI, pERT87-15/BamH and 16intron/TaqI polymorphism) was also applied to the deletion group which requested carrier detection. 41% of families referred for carrier detection were found to be informative for RFLP-analysis. Molecular analysis was efficiently applied to 12 fetuses in families with increased risk of DMD of the first or second trimester of gestation. Thus, using both the PCR and RFLP in over group affords an opportunity of prenatal diagnosis in 93% families. The results of direct DNA diagnosis of SMA in admitted to the clinic for suspected SMA are: in 18 out of 20 families (90%) the diagnosis of SMA was confirmed at the molecular level by revealing homozygous deletion of exons7 and/or 8 of the STNT at the probands. In 4 cases we performed prenatal diagnosis (PD) SMA. In 2 out of 4 fetuses we detected heterozygous deletion of the exons. The accuracy of PD in 2 fetuses informative for a deletion should be considered close to 100%. Conclusions: Thus, thanking the conspicuous progress in molecular analysis of the different gene, possibility for higher efficiency of PD in D/BMD, SMA families is quite evident. Deletion detection and carrier testing is a decisive step in elaborating a reliable strategy of prenatal diagnosis in families at high risk of DMD, SMA.
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