M. Poda

Mapping of the second Friedreich's ataxia (FRDA2) locus to chromosome 9p23-p11: evidence for further locus heterogeneity

Abstract. Friedreichs ataxia (FRDA), the most-common form of autosomal recessive ataxia, is inherited in most cases by a large expansion of a GAA triplet repeat in the first intron of the frataxin (X25) gene. Genetic heterogeneity in FRDA has been previously reported in typical FRDA families that do not link to the FRDA locus on chromosome 9q13. We report localization of a second FRDA locus (FRDAff2) to chromosome 9p23–9p11, and we provide evidence for further genetic heterogeneity of the disease, in a family with the classic FRDA phenotype.

Gender-modulated impact of apolipoprotein A5 gene (APOA5) -1131T>C and c.56C>G polymorphisms on lipids, dyslipidemia and metabolic syndrome in Turkish adults.

Abstract Background: Apolipoprotein A5 (APOA5) gene polymorphisms are usually associated with plasma triglyceride levels. We evaluated the relationship of the APOA5 −1131T>C and c.56C>G polymorphisms [single nucleotide polymorphism (SNP)] with serum lipids, dyslipidemia [low high-density lipoprotein (HDL)/high triglyceride] and the risk for metabolic syndrome (MS) in the Turkish Adult Risk Factor study. Methods: We genotyped SNPs using the Taqman allelic discrimination assays in 1564 Turkish adults (51.4% female, mean age 54.1±11.6 years). MS and dyslipidemia were defined using the criteria of the National Cholesterol Education Program. Results: For both SNPs, rare allele carriers had significantly higher fasting triglyceride levels in both genders, except the c.56G allele in men. The −1131C allele was associated with lower HDL cholesterol (HDL-C) levels in women. In relation to dyslipidemia, the c.56C>G and haplotype 1 had significant gender-genotype interactions (p<0.05). Otherwise, both SNPs were significantly associated with dyslipidemia after adjustment for risk factors in women. After similar adjustment, non-carriers of the haplotype 1 (odds ratio=4.1, p=0.003) increased the MS risk in women. However, no significant associations emerged between SNPs and HDL-C, dyslipidemia or MS in a similar analysis in men. Conclusions: Excess risk for low HDL-C, dyslipidemia and MS is associated with the rare alleles of the APOA5 SNPs and non-carriers of common haplotype in women. Clin Chem Lab Med 2008;46:778–84.

NATURAL HISTORY OF SMA IIIb: MUSCLE STRENGTH DECREASES IN A PREDICTABLE SEQUENCE AND MAGNITUDE

Objective: To assess the natural progression of muscle weakness in spinal muscular atrophy (SMA) IIIb. Methods: Ten patients with SMA IIIb were followed for at least 10 years. Age at disease onset varied between 9 and 18 years. Patients were initially seen 2 to 10 years after disease onset. They were evaluated at approximately 2, 5, 10, 15, and 20 years of disease duration depending on the timing of their initial visit after onset. Medical Research Council (MRC) scale was used with particular attention to proximal muscles. Results: The MRC grade declined with years in all of the muscles. The decline was usually not more than by one MRC grade for each 5-year period. There were 5–10 year periods when some muscles appeared to remain stationary. The succession of weakness was first triceps, then biceps and deltoid for upper extremity muscles and first thigh adductors, then iliopsoas, then quadriceps femoris, then hamstrings, thigh abductors, and gluteus maximus for lower extremity muscles. There was a remarkable uniformity between patients in the MRC grade for each muscle at each stage: in the first 5 years of the disease, triceps, iliopsoas, thigh adductors, and quadriceps femoris were the muscles which had noticeable weakness. Conclusions: These findings show that strength in spinal muscular atrophy IIIb decreases over time, explaining the progressive functional loss. The sequence of weakness in the lower extremities suggests that the disease starts segmentally involving the upper lumbar segments of the medulla spinalis initially. The slowness of the deterioration may have implications for clinical trials.

Segmental distribution of muscle weakness in SMA III: implications for deterioration in muscle strength with time1

We examined 26 spinal muscular atrophy type III (SMA III) patients with SMNt deletions, searching for possible segmental distribution of muscle weakness. In those with disease duration of < or = 11 years, the weakest muscles were upper lumbar innervated ones in the lower extremities. In the upper extremities, early involvement of triceps muscle suggested the possibility of lower cervical (C7) onset. Electrophysiologically, weaker muscles had a more severe reduction in the recruitment pattern, particularly in the lower extremities. However, severe reduction in recruitment was sometimes also observed in clinically strong muscles. In patients with disease duration of > or = 16 years and regardless of disease duration, in those with disease onset at < or = 3 years of age, weakness and severe electrophysiological changes were more widespread. These findings may suggest a progression in muscle weakness with time. When compared to 12 patients with Becker muscular dystrophy (BMD), early stage SMA III with weak iliopsoas-strong gluteus maximus stood in contrast to BMD with weak gluteus maximus-strong iliopsoas.

Genotypic and phenotypic presentation of transthyretin-related familial amyloid polyneuropathy (TTR-FAP) in Turkey

Transthyretin-related familial amyloid polyneuropathy (TTR-FAP) is an autosomal dominant disorder caused by mutations of the transthyretin (TTR) gene. The mutant amyloidogenic transthyretin protein causes the systemic accumulation of amyloid fibrils that result in organ dysfunction. TTR-associated FAP is a progressive and fatal disease, if left untreated, and should be considered in the differential diagnosis of any person presenting with a progressive polyneuropathy, particularly with accompanying autonomic involvement. The clinical, electrophysiological, histopathological, and genetic characteristics of 17 patients from Turkey (5 female, 13 male) from nine families with polyneuropathy and mutations in TTR were evaluated. Sequence analysis of the TTR gene revealed five mutations (Val30Met, Glu89Gln, Gly53Glu, Glu54Gly and Gly47Glu). Mean age at disease onset was 40.4 ± 13.9 years (range 21-66 years). The most commonly reported initial complaint was paresthesia in the feet (asymmetric in three patients). Three patients (2 male) with the Glu89Gln mutation presented with carpal tunnel syndrome. Two patients with the Gly53Glu mutation showed episodes of dysarthria and hemiparesis, consistent with this genotype. Seven patients died during the period of follow-up as a result of systemic involvement. Our study suggests that a cohort of patients from Turkey with TTR-FAP exhibits clinical and genetic heterogeneity.

Pretreatment with octreotide modulates iNOS gene expression, mimics surgical delay, and improves flap survival.

We aimed to evaluate the role of a synthetic somatostatin analogue in delay procedure of experimental skin flaps. Thirty-six rats were randomly divided into 2 groups of 18 each to compare the possible local ischemic effect of octreotide with that of surgical delay in the dorsal random pattern skin flap model. The inducible nitric oxide synthase gene expression was assessed in the flap territory at intervals of immediate, 24 and 48 hours after preconditioning. Histologic analysis was performed in rats at 48th hour and 3 additional rats were used for microangiography. A gradual increase of daily transcript levels was detected in both groups (P < 0.05). The differences of molecular and histologic findings between the groups were not distinctive. Pharmacologically preconditioned rat displayed relevant microvascular features. Forty rats were further grouped randomly into 4 groups of 10 each. In group 1 rats, flaps were raised and reinserted without any prior intervention. Group 2 rats underwent surgical delay procedure, whereas flap territories of the others received either saline solution or octreotide 1 week before the ultimate flap harvest. After another 7-day period, both delay procedures were found effective in improving flap viability (P < 0.01). Ischemia induced by octreotide favored to investigate its utility in delay phenomenon. Although it was not as effective as the surgical delay procedure, it may be a safe pharmacologic alternative to improve the flap survival.

Genotypic and phenotypic presentation of Glu89Gln mutation in Turkey

Background Transthyretin-related familial amyloid polyneuropathy (TTR-FAP) is an autosomal dominant disorder caused by mutations of the transthyretin (TTR) gene. More than 100 different mutations of the transthyretin gene are identified worldwide, but still the first described Val30Met is the most common one. The mutant amyloidogenic transthyretin protein causes systemic accumulation of amyloid fibrils that results in organ dysfunction and death. TTR-associated FAP is a progressive and fatal disease if left untreated and should be considered in the differential diagnosis of any patient with a progressive polyneuropathy, especially with an accompanying autonomic involvement.

A novel protein involved in heart development in Ambystoma mexicanum is localized in endoplasmic reticulum

The discovery of the naturally occurring cardiac non-function (c) animal strain in Ambystoma mexicanum (axolotl) provides a valuable animal model to study cardiomyocyte differentiation. In homozygous mutant animals (c/c), rhythmic contractions of the embryonic heart are absent due to a lack of organized myofibrils. We have previously cloned a partial sequence of a peptide cDNA (N1) from an anterior-endoderm-conditioned-medium RNA library that had been shown to be able to rescue the mutant phenotype. In the current studies we have fully cloned the N1 full length cDNA sequence from the library. N1 protein has been detected in both adult heart and skeletal muscle but not in any other adult tissues. GFP-tagged expression of the N1 protein has revealed localization of the N1 protein in the endoplasmic reticulum (ER). Results from in situ hybridization experiments have confirmed the dramatic decrease of expression of N1 mRNA in mutant (c/c) embryos indicating that the N1 gene is involved in heart development.