Ocular Features in 16 Brazilian Patients with Williams-Beuren Syndrome.

OBJECTIVES: Williams-Beuren Syndrome (WBS) is a multisystem disorder caused by the deletion of contiguous genes on chromosome 7q11.23. Ophthalmologic abnormalities and deficits in visual motor integration are important features of WBS. Here we describe our experience with Brazilian WBS patients and their ophthalmologic features. METHODS: Sixteen patients with confirmed WBS went through thorough ophthalmologic examination. RESULTS: The most frequent ocular findings in our group of patients were stellate iris pattern (81.2%), hyperopic astigmatism (50%), hyperopia (37.5%), tortuosity of retinal vessel (37.5%) and strabismus (18.7%). CONCLUSIONS: This is the second report of ophthalmologic abnormalities in a group of Brazilian individuals with WBS. It is extremely valuable that specific populations are studied so that clinical diagnosis can be refined and management of patients can be driven to the most common presentations of the disease.

Accurate, fast and cost-effective diagnostic test for monosomy 1p36 using real-time quantitative PCR.

Monosomy 1p36 is considered the most common subtelomeric deletion syndrome in humans and it accounts for 0.5-0.7% of all the cases of idiopathic intellectual disability. The molecular diagnosis is often made by microarray-based comparative genomic hybridization (aCGH), which has the drawback of being a high-cost technique. However, patients with classic monosomy 1p36 share some typical clinical characteristics that, together with its common prevalence, justify the development of a less expensive, targeted diagnostic method. In this study, we developed a simple, rapid, and inexpensive real-time quantitative PCR (qPCR) assay for targeted diagnosis of monosomy 1p36, easily accessible for low-budget laboratories in developing countries. For this, we have chosen two target genes which are deleted in the majority of patients with monosomy 1p36: PRKCZ and SKI. In total, 39 patients previously diagnosed with monosomy 1p36 by aCGH, fluorescent in situ hybridization (FISH), and/or multiplex ligation-dependent probe amplification (MLPA) all tested positive on our qPCR assay. By simultaneously using these two genes we have been able to detect 1p36 deletions with 100% sensitivity and 100% specificity. We conclude that qPCR of PRKCZ and SKI is a fast and accurate diagnostic test for monosomy 1p36, costing less than 10 US dollars in reagent costs.

Rapid and inexpensive screening of genomic copy number variations using a novel quantitative fluorescent PCR method.

Detection of human microdeletion and microduplication syndromes poses significant burden on public healthcare systems in developing countries. With genome-wide diagnostic assays frequently inaccessible, targeted low-cost PCR-based approaches are preferred. However, their reproducibility depends on equally efficient amplification using a number of target and control primers. To address this, the recently described technique called Microdeletion/Microduplication Quantitative Fluorescent PCR (MQF-PCR) was shown to reliably detect four human syndromes by quantifying DNA amplification in an internally controlled PCR reaction. Here, we confirm its utility in the detection of eight human microdeletion syndromes, including the more common WAGR, Smith-Magenis, and Potocki-Lupski syndromes with 100% sensitivity and 100% specificity. We present selection, design, and performance evaluation of detection primers using variety of approaches. We conclude that MQF-PCR is an easily adaptable method for detection of human pathological chromosomal aberrations.

Simple, rapid and inexpensive quantitative fluorescent PCR method for detection of microdeletion and microduplication syndromes.

Because of economic limitations, the cost-effective diagnosis of patients affected with rare microdeletion or microduplication syndromes is a challenge in developing countries. Here we report a sensitive, rapid, and affordable detection method that we have called Microdeletion/Microduplication Quantitative Fluorescent PCR (MQF-PCR). Our procedure is based on the finding of genomic regions with high homology to segments of the critical microdeletion/microduplication region. PCR amplification of both using the same primer pair, establishes competitive kinetics and relative quantification of amplicons, as happens in microsatellite-based Quantitative Fluorescence PCR. We used patients with two common microdeletion syndromes, the Williams-Beuren syndrome (7q11.23 microdeletion) and the 22q11.2 microdeletion syndromes and discovered that MQF-PCR could detect both with 100% sensitivity and 100% specificity. Additionally, we demonstrated that the same principle could be reliably used for detection of microduplication syndromes, by using patients with the Lubs (MECP2 duplication) syndrome and the 17q11.2 microduplication involving the NF1 gene. We propose that MQF-PCR is a useful procedure for laboratory confirmation of the clinical diagnosis of microdeletion/microduplication syndromes, ideally suited for use in developing countries, but having general applicability as well.

Identification of Polynesian mtDNA haplogroups in remains of Botocudo Amerindians from Brazil.

There is a consensus that modern humans arrived in the Americas 15,000-20,000 y ago during the Late Pleistocene, most probably from northeast Asia through Beringia. However, there is still debate about the time of entry and number of migratory waves, including apparent inconsistencies between genetic and morphological data on Paleoamericans. Here we report the identification of mitochondrial sequences belonging to haplogroups characteristic of Polynesians in DNA extracted from ancient skulls of the now extinct Botocudo Indians from Brazil. The identification of these two Polynesian haplogroups was confirmed in independent replications in Brazil and Denmark, ensuring reliability of the data. Parallel analysis of 12 other Botocudo individuals yielded only the well-known Amerindian mtDNA haplogroup C1. Potential scenarios to try to help understand these results are presented and discussed. The findings of this study may be relevant for the understanding of the pre-Columbian and/or post-Columbian peopling of the Americas.

A new case of keratoconus associated with Williams-Beuren syndrome.

BACKGROUND: Williams-Beuren syndrome is a multisystemic genetic disorder caused by a contiguous gene deletion at 7q11.23. Keratoconus is a complex disease and it is suspected to have a genetic origin, although the specific gene responsible for keratoconus has not been identified. Although there are several ocular features in Williams-Beuren syndrome, keratoconus is not regularly described as part of this syndrome. PURPOSE: To report a new patient with keratoconus and Williams-Beuren syndrome. DISCUSSION: This is the third case of an association between Williams-Beuren syndrome and keratoconus. The authors believe that the Williams-Beuren syndrome chromosome region can be a possible target for further investigation as the genetic basis of keratoconus.

Recovering mitochondrial DNA lineages of extinct Amerindian nations in extant homopatric Brazilian populations.

BACKGROUND: Brazilian Amerindians have experienced a drastic population decrease in the past 500 years. Indeed, many native groups from eastern Brazil have vanished. However, their mitochondrial mtDNA haplotypes, still persist in Brazilians, at least 50 million of whom carry Amerindian mitochondrial lineages. Our objective was to test whether, by analyzing extant rural populations from regions anciently occupied by specific Amerindian groups, we could identify potentially authentic mitochondrial lineages, a strategy we have named 'homopatric targeting'. RESULTS: We studied 173 individuals from Queixadinha, a small village located in a territory previously occupied by the now extinct Botocudo Amerindian nation. Pedigree analysis revealed 74 unrelated matrilineages, which were screened for Amerindian mtDNA lineages by restriction fragment length polymorphism. A cosmopolitan control group was composed of 100 individuals from surrounding cities. All Amerindian lineages identified had their hypervariable segment HVSI sequenced, yielding 13 Amerindian haplotypes in Queixadinha, nine of which were not present in available databanks or in the literature. Among these haplotypes, there was a significant excess of haplogroup C (70%) and absence of haplogroup A lineages, which were the most common in the control group. The novelty of the haplotypes and the excess of the C haplogroup suggested that we might indeed have identified Botocudo lineages. To validate our strategy, we studied teeth extracted from 14 ancient skulls of Botocudo Amerindians from the collection of the National Museum of Rio de Janeiro. We recovered mtDNA sequences from all the teeth, identifying only six different haplotypes (a low haplotypic diversity of 0.8352 ± 0.0617), one of which was present among the lineages observed in the extant individuals studied. CONCLUSIONS: These findings validate the technique of homopatric targeting as a useful new strategy to study the peopling and colonization of the New World, especially when direct analysis of genetic material is not possible.

Expression of different classes of immunoglobulin in intraepithelial plasma cells of the Harderian gland of domestic ducks Anas platyrhynchos.

The Harderian gland of chickens contains numerous plasma cells and is considered as a peripheral lymphoid organ. Data about this gland in other avian species are scarce or inexistent. Considering that ducks show some unique characteristics regarding the immune system, which are important in evolutionary context, and that unusual location of plasma cells into the epithelium was recently described in primitive avian species, here we investigated the occurrence and characterized intraepithelial plasma cells in the Harderian gland of ducks, according to the immunoglobulin produced. Numerous intraepithelial plasma cells were found confined to the Harderian gland ducts. Plasma cells were also found in the ducts lamina propria. IgM-positive cells were the most abundant into the epithelium. In contrast, IgY- or IgA-positive cells were predominant in the lamina propria. The constancy of intraepithelial plasma cells in all specimens examined indicates that they may be essential mediator for an effective immunesurvaillance of the ocular mucosa.