Molecular genetic diagnostics of tuberous sclerosis complex in Bulgaria: six novel mutations in the TSC1 and TSC2 genes.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the development of hamartomas localized in various tissues which can occur in the skin, brain, kidney and other organs. TSC is caused by mutations in the TSC1 and TSC2 genes. Here we report the results from the first molecular testing of 16 Bulgarian patients and one Romanian patient in whom we found six novel mutations: four in the TSC22 gene, of which one is nonsense, two frame shift and one large deletion of 16 exons; and two in the TSC1 gene, one nonsense and other frame shift. In addition, we detected 10 previously reported mutations; some of which are described only once in the literature. Our data is similar to the previous studies with exception of the larger number of TSC1 mutations than that reported in the literature data. In total, 40% (4/10) of the mutation in the TSC2 gene are located in the GTPase-activating protein domain, while 50% (3/6) are in the TSC1 gene and clustered in exon 15. All the cases represent the typical clinical symptoms and meet the clinical criteria for TSC diagnosis. In 35% of our cases the family history was positive. Our results add novel findings in the genetic heterogeneity and pathogenesis of TSC. The genetic heterogeneity might correlate to the clinical variability among the TSC-affected families, which makes the genetic counselling a real challenge.

[The experience of application of target sequencing in molecular diagnostic of mucoviscidosis.]

The mucoviscidosis is one of frequent monogenic diseases. In Russia, in case of mucoviscidosis carrying out of DNA-diagnostic is optional. However, its application permits shortening time of diagnosing, increasing efficiency of of therapeutic treatment and preventing secondary manifestation of disease in family. The DNA-diagnostic using panels on frequent mutations in gene CFTR is recommended in cases of uncertain clinical picture and under borderline values of specific laboratory indices. In Russia, application of such panels permit detecting up to 90% of pathological alleles in gene CFTR. To detect more rare alleles the Sanger sequencing is traditionally applied. Lately, highly productive sequencing techniques became available to detect rare mutations. The actual article presents evaluation of efficiency of application of test-system based on technology of target sequencing for detecting mutations unidentified at primary DNA-diagnostic. Besides, in two patients with mucoviscidosis the application of highly productive sequencing techniques permitted to identify previously unknown nonsense mutations Q1038X (c.3112C>T) и W1310X (c.3930G>A).

[Analysis of Heteroplasmy in the Major Noncoding Region of Mitochondrial DNA in the Blood and Atherosclerotic Plaques of Carotid Arteries].

For identification of somatic mitochondrial DNA (mtDNA) mutations, the mtDNA major noncoding region (D-loop) sequence in blood samples and carotid atherosclerosis plaques from patients with atherosclerosis was analyzed. Five point heteroplasmic positions were observed in 4 of 23 individuals (17%). Only in two cases could heteroplasmy have resulted from somatic mutation, whereas three heteroplasmic positions were found in both vascular tissue and blood. In addition, length heteroplasmy in a polycytosine stretches was registered at nucleotide positions 303-315 in 16 individuals, and also in the 16184-16193 region--in four patients. The results suggest that somatic mtDNA mutations can occur during atherosclerosis, but some heteroplasmic mutations may appear in all tissues, possibly being inherited.

[Necessity of individual approach to evaluating the level of fatigue during prolonged work in the mountains]. / O neobkhodimosti individualnogo podkhoda k otsenke stepeni utomleniia pri rabote v usloviiakh dlitelnoi vysokogornoi vakhty.

Capacity to the physical work and functional status were studied during the prolonged (1 year) work in the mountainous conditions (3,600 m above sea level). The fatigue grade and capacity level were proved to depend on individual adaptation to the mountainous conditions.