RESUMEN
Ataxia-Telangiectasia [AT] is a rare human neurodegenerative autosomal recessive multisystem disease that is characterized by a wide range of features including, progressive cerebellar ataxia with onset during infancy, occulocutaneous telangiectasia, susceptibility to neoplasia, occulomotor disturbances, chromosomal instability and growth and developmental abnormalities. Mitochondrial DNA [mtDNA] has the only non-coding regions at the displacement loop [D-loop] region that contains two hypervariable segments [HVS-I and HVS-II] with high polymorphism. We investigated mt-DNA deletions and haplogroups in AT patients. In this study, 24 Iranian patients suffering from AT and 100 normal controls were examined. mt-DNA was extracted from whole blood and examined by 6 primers for existence of mitochondrial deletions. We also amplified and sequenced the mtDNA HVS-I by standard sequencing techniques. mtDNA deletions were observed in 54.1% [13/24] of patients [8.9 kb deletion in all samples, 5.0 kb in one and 7.5 kb in two patients], representing mtDNA damage which may be due to oxidative stress in mitochondria. Our results showed that there is no association between mtDNA haplogroups and AT. This data may indicate involvement of mitochondrial damage in the pathogenesis of AT
RESUMEN
Primary immunodeficiency disorders are a heterogeneous group of genetic disorders, with different modes of inheritance, consisting of more than 100 different types. We constructed the DNA banking of primary immunodeficiency disorders for the first time in Iran. The DNA of 31 immunodeficient patients and their families [total of 92 samples] were collected, as the first step for construction of DNA banking. DNA was isolated from whole blood by salting out method. Among our patients, Common variable immunodeficiency was the most common disorder, followed by X-linked agammaglobulinemia, Ataxia-telangiectasia, Chronic granulomatous disease, Severe combined immunodeficiency, Hyper IgM syndromes, and Leukocyte adhesion defects. DNA banking is a useful method for further detection of mutation in immunodeficient patients and prenatal diagnosis for presence or absence of the disorder in the fetus which can be confirmed by molecular genetics testing
RESUMEN
Ataxia-Telangiectasia [AT] is an autosomal recessive disorder involving cerebellar degeneration, immunodeficiency, radiation sensitivity and cancer predisposition. The ATM gene on human chromosome 11q22.3 has recently been identified as the gene responsible for ataxia-telangiectasia [AT]. The gene mutated in AT, which has been designated as the ATM gene, encodes a large protein kinase with a PI-3 kinase-related domain. More than 100 mutations are broadly distributed throughout the ATM gene. The large size of the ATM gene [66 exons spanning approximate 150kb of genomic DNA] together with the diversity and broad distribution of mutations in AT patients, greatly limits the utility of direct mutation screening as a diagnostic tool. In this study, 20 families with at least one affected child clinically suspected to have ataxia-telagiectasia were examined and their DNA was extracted and amplified with standard methods. Sequencing methods were used to detect the new point mutation. Four exons which were hot spots for point mutations in ATM gene were detected by PCR-SSCP or PCR-RFLP