The present study demonstrates the severity of IDH in Bahia and confirms that its diagnosis is based almost exclusively on clinical aspects of the disease. Serological testing for HTLV-I and careful follow-up is recommended for all children with chronic, relapsing, severe eczema in regions where HTLV-I is endemic.
Advanced glycation end products (AGEs) may play an important role in the pathogenesis of chronic diabetic complications and in the natural process of biological aging.
Huntington disease (HD) is caused by an expansion of a CAG repeat. This repeat is a dynamic mutation that tends to undergo intergenerational instability. We report the analysis of the CAG repeat in a large population sample (2,000 chromosomes) covering all regions of Portugal, and a haplotype study of (CAG) n and (CCG) n repeats in 140 HD Portuguese families. Intermediate class 2 alleles represented 3.0% of the population; and two expanded alleles (36 and 40 repeats, 0.11%) were found. There was no evidence for geographical clustering of the intermediate or expanded alleles. The Portuguese families showed three different HD founder haplotypes associated with 7-, 9-or 10-CCG repeats, suggesting the possibility of different origins for the HD mutation among this population. The haplotype carrying the 7-CCG repeat was the most frequent, both in normal and in expanded alleles. In general, we propose that three mechanisms, occurring at different times, may lead to the evolution from normal CAGs to full expansion: first, a mutation bias towards larger alleles; then, a stepwise process that could explain the CAG distributions observed in the more recent haplotypes; and, finally, a pool of intermediate (class 2) alleles more prone to give rise to expanded HD alleles.
Huntington disease (HD) is a neurodegenerative, autosomal dominant disorder of late-onset, caused by the expansion of a CAG repeat in the coding region of the gene. Ours is the reference laboratory for genetic testing in HD, in Portugal, since 1998; 90.1% of all 158 families known were identified for the first time, including patients with unusual presentation or without family history. A total of 338 genetic tests were performed: 234 for diagnosis, 96 for presymptomatic and four for prenatal testing (four were done for family studies). Most referring physicians were neurologists (90.6%); 82.8% of all clinical diagnosis were confirmed, while 83.1% of those sent for exclusion were in fact excluded. In presymptomatic testing, an excess of female subjects (59.4%) was again verified; 37.5% of the consultands were found to be carriers. None of the foetuses, in four prenatal tests, were mutation carriers. One juvenile case was inherited from her mother. Our patient population is very similar to others described so far, namely in terms of mean age at onset and (CAG) n distribution, except perhaps for a higher frequency of large normal (class 2) alleles (3.7%). We also identify cases posing particular problems for genetic counselling, such as, 'homozygosity' that can pose a serious ethical dilemma, carriers of large normal alleles, and 'homoallelism' for a normal gene, which will demand further procedures and may delay results in presymptomatic and prenatal testing.
Capsule The Skylark Alauda arvensis had the highest overall mortality in ten Northern Portuguese wind farms surveyed between 2006 and 2011. Analysis from the integration of conventional and molecular techniques suggest a sex and age biased mortality affecting mainly adult males (90.9%), which may be related to their characteristic breeding male song-flights making them highly vulnerable to collision with wind turbines. The results highlight the added value of more complete population impact assessments that go beyond simple carcass identification at wind farms.
Telomere length has been used as a proxy of fitness, aging and lifespan in vertebrates. In the last decade, dozens of articles reporting on telomere dynamics in the fields of ecology and evolution have been published for a wide range of taxa. With this growing interest, it is necessary to ensure the accuracy and reproducibility of telomere length measurement techniques. Real-time quantitative PCR (qPCR) is routinely applied to measure relative telomere length. However, this technique is highly sensitive to several methodological variables and the optimization of qPCR telomere assays remains highly variable between studies. Therefore, standardized guidelines are required to enable the optimization of robust protocols, and to help in judging the validity of the presented results. This review provides an overview of preanalytical and analytical factors that can lead to qPCR inconsistencies and biases, including: (a) sample type, collection and storage; (b) DNA extraction, storage and quality; (c) qPCR primers, laboratory reagents, and assay conditions; and (d) data analysis. We propose a minimum level of information for publication of qPCR telomere assays in evolutionary ecology considering the methodological pitfalls and sources of error. This review highlights the complexity of the optimization and validation of qPCR for telomere measurement per se, demonstrating the importance of transparency and clarity of reporting methodological details required for reliable, reproducible and comparable qPCR telomere assays. We encourage efforts to implement standardized protocols that ensure the rigour and quality of telomere dynamics studies.
K E Y W O R D SDNA extraction, qPCR conditions, real-time quantitative PCR, sampling, telomere measurement
The analysis of telomere dynamics in birds is a growing research field providing important findings on ecological and environmental variations in individuals’ aging, fitness and lifespan. Real‐time quantitative PCR (qPCR) has gained much interest for the evaluation of telomere length in birds. However, the assessment of several key preanalytical and analytical factors to optimize the method for achieving reproducible results, and the influence of these factors on the conclusions of each study, have been generally overlooked. In this study, we assessed the performance of eight commercially‐available qPCR master mixes in the amplification of telomere fragments in two bird species (zebra finch Taeniopygia guttata and red‐billed chough Pyrrhocorax pyrrhocorax). We observed that qPCR master mixes influence the telomere primer binding to target sequences and the amplification specificity within and between bird species, although PCR amplification efficiencies were very close to 100% for all master mixes. These findings indicated that the suitability of the master mix and other analytical factors must be carefully evaluated before starting a telomere dynamics study, especially when the technique has not previously been used in the species. We also showed that optimal PCR amplification efficiencies do not translate to good qPCR telomere assays, and that inference about amplification specificity based only on melting curve data can lead to misleading conclusions. Overall, this work highlights the complexity of qPCR optimization for the study of telomere length in birds.
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