Abstract. Breast cancer is currently the most common type of cancer in females. The majority of the hereditary forms of breast cancer are caused by mutations in the BRCA1 and BRCA2 genes, whose main function is the DNA repair of double-strand breaks. Genetic testing of females with a family history of breast cancer is recommended to determine their hereditary predisposition for this type of cancer. The variants with no clear clinical significance may represent a diagnostic challenge when performing targeted resequencing. In this study, DNA samples were obtained from 24 breast cancer patients (mean age, 35±10 years) with a positive family history and from 71 age-matched healthy controls. Informed consent was obtained from all the subjects. Sequence-targeted BRCA1 and BRCA2 libraries were prepared using the TruSeq Custom Amplicon method and sequenced on the Illumina MiSeq system. A wide range of variants were identified in the BRCA1 and BRCA2 genes. Two pathological̸presumably pathological variants were detected in the breast cancer patient group: a mutation in BRCA2 at the chromosomal (chr) position chr13:32890665, which affected the first position of the 5' splice region following exon 2; and a mutation in BRCA1 at chr17:41219635, causing an in-frame triple nucleotide deletion of valine 1688 (8.3%). In the patient and control groups, 7 likely polymorphic variants and 13 common variants were detected in the BRCA1 and BRCA2 genes. To the best of our knowledge, this study was the first to identify 3 common polymorphisms in BRCA2, characteristic solely of the Bulgarian population, including chr13:32973737, T̸-, a single-nucleotide polymorphism (SNP) within the 3'-UTR of exon 27; chr13:32973280, A̸-, a mononucleotide deletion within the 5'-UTR of exon 27; and chr13:32973924, T̸-, a mononucleotide deletion downstream of the gene sequence. To the best of our knowledge, this study was the first to apply next-generation sequencing of the BRCA1 and BRCA2 genes in a Bulgarian population, prompting further investigation for local founder mutations and variants characteristic for this particular region.
Early infantile epileptic encephalopathy (EIEE) is a disorder with variable genetic heterogeneity. Symptoms are mostly presented with generalised epileptic seizures with an infantile onset and progressive neurodevelopmental delay. Early infantile epileptic encephalopathy13 is caused by mutations in the SCN8A gene, which encodes the neuronal voltage-gated sodium channel a subunit (Nav1.6) and plays a major role in neuronal excitability. Describing the wide clinical variability of previously reported cases of patients carrying the same mutation, we demonstrate the complexity of the disease and the necessity of correctly correlating the phenotype with the genotype. Here, we present a minireview and a case report of EIEE13 involving the rare p.Arg1872Gln mutation in the SCN8A gene. We used targeted next-generation sequencing to examine a six-year-old girl with complex partial seizures from the left temporal lobe since 4 months of age. The condition was difficult to control with medication and the seizures evolved to generalised tonic-clonic seizures after the age of 3 years. Neurodevelopment in the child became severely delayed although seizures were as rare as 1 in every 5-10 months. ff heterozygous missense mutation in the SCN8A gene (NM_014191.3:c.5616G > A, NP_055006.1:p.Arg1872Gln) was found. The variant was validated by Sanger sequencing. We suggest that this SCN8A mutation has a primary neurodegenerative effect leading to brain atrophy and intellectual disability (with or without autism) that is partially independent of its epileptogenic effect. Our results demonstrate that the application of large panels with clinically-associated genes is essential for identifying rare mutations in individuals with disorders of unknown etiology.
The growth and 2-phenylethanol (2-PE) biosynthesis of three ascomycetous yeasts belonging to the genera Saccharomyces and Kluyveromyces, able to synthesize 2-PE, was studied. The key growth kinetic parameters were calculated and the comparison of the obtained results revealed that the newly isolated K. marxianus 35 strain had higher potential for 2-PE production. It was characterized with a lower growth yield coefficient and a higher substrate uptake rate and 2-PE production rate in comparison with the other two yeast strains. The assays of key enzymes from the Ehrlich pathway (aminotransferase, pyruvate decarboxylase and alcohol dehydrogenase) showed that K. marxianus 35 also expresses a nearly twofold higher level of activities. Furthermore, the biotransformation capacity for 2-PE production was investigated through measurement of 2-Phe residual concentration. This concentration was twofold lower in K. marxianus 35 and the efficiency was found to be 73 % for this strain. These values for K. marxianus 1984 and S. cerevisiae 584 were 58 % and 32 %, respectively. In order to comprehensively examine the potential of K. marxianus 35 for 2-PE biosynthesis, the sequence variability in the genes encoding key enzymes from the Ehrlich pathway were investigated. The obtained data suggest that, apart from physiological advantages gained, Kluyveromyces yeasts have probably undergone substantial evolutionary gene alterations resulting in higher enzymatic activities and better 2-PE transformation potential. Based on the performed comparative analysis, it was shown that among the studied 2-PE producers, K. marxianus 35 has several advantages which make this strain a promising candidate for industrial processes.
Congenital anomalies affect 1% to 2% of the newborns. The urinary tract and the kidneys are involved in 4-5% of the cases while upper-extremities abnormalities are present in 10%. Certain anomalies occur in isolation, whereas others are associated with systemic conditions. The prenatal detection of fetal anomalies compatible with life is a challenge for both the parents and the physician. The prognosis for the fetus/newborn and the reproductive decisions of the family largely depend on the causes underlying the disease. The reported case is of a G2P1 pregnant woman referred for routine ultrasound scan at 24 weeks of gestation (w.g.). The fetus had growth retardation, right kidney agenesis, bilateral absence of radial bones and thumbs, radial deviation of the wrists, and short humeri. Nuchal fold thickness was 5 mm and there was a single umbilical artery. After termination of pregnancy, SNP array genotyping and next-generation sequencing of targeted candidate-genes were performed trying to clarify the etiology of the fetal polymalformative syndrome. A new hypomorphic mutation in FANCD2 gene was found to underlie this fetal anomaly. The case illustrates that patients/families affected by rare monogenic disorders may benefit from application of modern technologies like microarrays and NGS.
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