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Prenatal exposure to misoprostol and vascular disruption defects: A case-control study

Prenatal exposure to misoprostol has been associated with Moebius and limb defects. Vascular disruption has been proposed as the mechanism for these teratogenic effects. The present study is a multicenter, case-control study that was designed to compare the frequency of prenatal misoprostol use between mothers of Brazilian children diagnosed with vascular disruption defects and matched control mothers of children diagnosed with other types of defects. A total of 93 cases and 279 controls were recruited in eight participating centers. Prenatal exposure was identified in 32 infants diagnosed with vascular disruption defects (34.4%) compared with only 12 (4.3%) in the control group (P<0.0000001). Our data suggest that prenatal exposure to misoprostol is associated to the occurrence of vascular disruption defects in the newborns.

Detailed haplotype analysis at the TP53 locus in p.R337H mutation carriers in the population of Southern Brazil: evidence for a founder effect

Due to patterns of migration, selection, and population expansion, founder effects are common among humans. In Southern Brazil, a recurrent TP53 mutation, p.R337H, is detected in families with cancer predisposition. We have used whole locus resequencing and high‐density single nucleotide polymorphism (SNP) genotyping to refine TP53 locus haplotype definitions. Haplotyping of 12 unrelated p.R337H carriers using a set of 29 tag SNPs, revealed that all subjects carried the same haplotype, and presence of the mutation on this haplotype was confirmed by allele‐specific PCR. The probability that this haplotype occurs independently in all index cases was of 3.1×10−9, demonstrating a founder effect. Analysis of the patterns of 103 tumors diagnosed in 12 families showed that the presence of p.R337H is associated with multiple cancers of the Li‐Fraumeni Syndrome (LFS) spectrum, with relatively low penetrance before the age of 30 but a lifetime risk comparable to classical LFS. The p.R337H families are mostly distributed along a road axis historically known as the main route used by merchants of Portuguese origin in the XVIII and XIX century. This historical circumstance and the relatively low penetrance before the age of 30 may have contributed to the maintenance of this pathogenic mutation in a large, open population. Hum Mutat 30:1–8, 2009.

A specific mutation in the distant sonic hedgehog (SHH) cis-regulator (ZRS) causes Werner mesomelic syndrome (WMS) while complete ZRS duplications underlie Haas type polysyndactyly and preaxial polydactyly (PPD) with or without triphalangeal thumb†

Werner mesomelic syndrome (WMS) is an autosomal dominant disorder with unknown molecular etiology characterized by hypo‐ or aplasia of the tibiae in addition to the preaxial polydactyly (PPD) of the hands and feet and/or five‐fingered hand with absence of thumbs. We show that point mutations of a specific nucleotide within the sonic hedgehog (SHH) regulatory region (ZRS) cause WMS. In a previously unpublished WMS family, we identified the causative G>A transition at position 404 of the ZRS, and in six affected family members of a second WMS family we found a 404G>C mutation of the ZRS. The 404G>A ZRS mutation is known as the “Cuban mutation” of PPD type II (PPD2). Interestingly, the index patient of that family had tibial hypoplasia as well. These data provide the first evidence that WMS is caused by a specific ZRS mutation, which leads to strong ectopic SHH expression. In contrast, we show that complete duplications of the ZRS region lead to type Haas polysyndactyly or triphalangeal thumb‐polysyndactyly syndrome, but do not affect lower limb development. We suggest the term “ZRS‐associated syndromes” and a clinical subclassification for the continuum of limb malformations caused by different molecular alterations of the ZRS. Hum Mutat 30:1–9, 2009.

Xp-duplications with and without sex reversal

Duplications in Xp including the DSS (dosage sensitive sex reversal) region cause male to female sex reversal. We investigated two patients from families with Xp duplications. The first case was one of two sisters with karyotype 46,XY, der(22), t(X;22)(p11.3;p11)mat and unambiguous female genitalia. The living sister was developmentally retarded, and showed multiple dysmorphic features and an acrocallosal syndrome. The second case was a boy with a maternally inherited direct duplication of Xp21.3-pter with the breakpoint close to the DSS locus. He had multiple abnormalities and micropenis, but otherwise unambiguous male genitalia. We performed quantitative Southern blot analysis with probes from Xp22.13 to p21.2 to define the duplicated region. Clinical, cytogenetic, and molecular data from both patients were compared with those of previously reported related cases. A comparison of the extragenital symptoms revealed no differences between patients with or without sex reversal. In both cases, the symptoms were non-specific. Among 22 patients with a duplication in Xp, nine had unambiguous female genitalia and a well-documented duplication of the DSS region. Two patients with duplication of DSS showed ambiguous external genitalia. From these data, we conclude that induction of testicular tissue may start in these patients, but that the type of genitalia depends on the degree of subsequent degeneration by a gene in DSS.

More epigenetic hits than meets the eye: microRNAs and genes associated with the tumorigenesis of retinoblastoma

Retinoblastoma (RB), a childhood neoplasia of the retinoblasts, can occur unilaterally or bilaterally, with one or multiple foci per eye. RB is associated with somatic loss of function of both alleles of the tumor suppressor gene RB1. Hereditary forms emerge due to germline loss of function mutations in RB1 alleles. RB has long been the prototypic “model” cancer ever since Knudsons “two-hit” hypothesis. However, a simple two-hit model for RB is challenged by an increasing number of studies documenting additional hits that contribute to RB development. Here we review the genetics and epigenetics of RB with a focus on the role of small non-coding RNAs (microRNAs) and on novel findings indicating the relevance of DNA methylation in the development and prognosis of this neoplasia. Studies point to an elaborated landscape of genetic and epigenetic complexity, in which a number of events and pahtways play crucial roles in the origin and prognosis of RB. These include roles for microRNAs, inprinted loci, and parent-of-origin contributions to RB1 regulation and RB progression. This complexity is also manifested in the structure of the RB1 locus itself: it includes numerous repetitive DNA segments and retrotransposon insertion elements, some of which are actively transcribed from the RB1 locus. Altogether, we conclude that RB1 loss of function represents the tip of an iceberg of events that determine RB development, progression, severity, and disease risk. Comprehensive assessment of personalized RB risk will require genetic and epigenetic evaluations beyond RB1 protein coding sequences.

Clinical Characterization and Risk Profile of Individuals Seeking Genetic Counseling for Hereditary Breast Cancer in Brazil

Hereditary breast cancer (HBC) accounts for 5–10% of breast cancer cases and it significantly increases the lifetime risk of cancer. Our objective was to evaluate the sociodemographic variables, family history of cancer, breast cancer (BC) screening practices and the risk profile of cancer affected or asymptomatic at-risk women that undergo genetic counseling for hereditary breast cancer in public Brazilian cancer genetics services. Estimated lifetime risk of BC was calculated for asymptomatic women using the Gail and Claus models. The majority of women showed a moderate lifetime risk of developing BC, with an average risk of 19.7% and 19.9% by the Gail and Claus models, respectively. The average prior probability of carrying a BRCA1/2 gene mutation was 16.7% and overall only 32% fulfilled criteria for a hereditary breast cancer syndrome as assessed by family history. We conclude that a significant number of individuals at high-risk for HBC syndromes may not have access to the benefits of cancer genetic counseling in these centers. Contributing factors may include insufficient training of healthcare professionals, disinformation of cancer patients; difficult access to genetic testing and/or resistance in seeking such services. The identification and understanding of these barriers is essential to develop specific strategies to effectively achieve cancer risk reduction in this and other countries were clinical cancer genetics is not yet fully established.

Prevalence of the BRCA1 founder mutation c.5266dupin Brazilian individuals at-risk for the hereditary breast and ovarian cancer syndrome

About 5-10% of breast and ovarian carcinomas are hereditary and most of these result from germline mutations in the BRCA1 and BRCA2 genes. In women of Ashkenazi Jewish ascendance, up to 30% of breast and ovarian carcinomas may be attributable to mutations in these genes, where 3 founder mutations, c.68_69del (185delAG) and c.5266dup (5382insC) in BRCA1 and c.5946del (6174delT) in BRCA2, are commonly encountered. It has been suggested by some authors that screening for founder mutations should be undertaken in all Brazilian women with breast cancer. Thus, the goal of this study was to determine the prevalence of three founder mutations, commonly identified in Ashkenazi individuals in a sample of non-Ashkenazi cancer-affected Brazilian women with clearly defined risk factors for hereditary breast and ovarian cancer (HBOC) syndrome. Among 137 unrelated Brazilian women from HBOC families, the BRCA1 c.5266dup mutation was identified in seven individuals (5%). This prevalence is similar to that encountered in non-Ashkenazi HBOC families in other populations. However, among patients with bilateral breast cancer, the frequency of c.5266dup was significantly higher when compared to patients with unilateral breast tumors (12.1% vs 1.2%, p = 0.023). The BRCA1 c.68_69del and BRCA2 c.5946del mutations did not occur in this sample. We conclude that screening non-Ashkenazi breast cancer-affected women from the ethnically heterogeneous Brazilian populations for the BRCA1 c.68_69del and BRCA2 c.5946del is not justified, and that screening for BRCA1 c.5266dup should be considered in high risk patients, given its prevalence as a single mutation. In high-risk patients, a negative screening result should always be followed by comprehensive BRCA gene testing. The finding of a significantly higher frequency of BRCA1 c.5266dup in women with bilateral breast cancer, as well as existence of other as yet unidentified founder mutations in this population, should be further assessed in a larger well characterized high-risk cohort.

Influence of MDM2 and MDM4 on development and survival in hereditary retinoblastoma.

Retinoblastoma (RB) accounts for 3% of all childhood malignancies, with different incidences around the world. This malignancy results from loss‐of‐function of both RB1 alleles although other genes, like MDM2 and MDM4, have been proposed to be involved in tumor development.

Huntington disease and Huntington disease-like in a case series from Brazil

The aim of this study was to identify the relative frequency of Huntingtons disease (HD) and HD‐like (HDL) disorders HDL1, HDL2, spinocerebellar ataxia type 2 (SCA2), SCA17, dentatorubral‐pallidoluysian degeneration (DRPLA), benign hereditary chorea, neuroferritinopathy and chorea‐acanthocytosis (CHAC), in a series of Brazilian families. Patients were recruited in seven centers if they or their relatives presented at least chorea, besides other findings. Molecular studies of HTT, ATXN2, TBP, ATN1, JPH3, FTL, NKX2‐1/TITF1 and VPS13A genes were performed. A total of 104 families were ascertained from 2001 to 2012: 71 families from South, 25 from Southeast and 8 from Northeast Brazil. There were 93 HD, 4 HDL2 and 1 SCA2 families. Eleven of 104 index cases did not have a family history: 10 with HD. Clinical characteristics were similar between HD and non‐HD cases. In HD, the median expanded (CAG)n (range) was 44 (40–81) units; R2 between expanded HTT and age‐at‐onset (AO) was 0.55 (p = 0.0001, Pearson). HDL2 was found in Rio de Janeiro (2 of 9 families) and Rio Grande do Sul states (2 of 68 families). We detected HD in 89.4%, HDL2 in 3.8% and SCA2 in 1% of 104 Brazilian families. There were no cases of HDL1, SCA17, DRPLA, neuroferritinopathy, benign hereditary chorea or CHAC. Only six families (5.8%) remained without diagnosis.

Hereditary retinoblastoma transmitted by maternal germline mosaicism.

Investigating transmission of a constitutive, g78238C > T (R552X), RB1 mutation in four affected children descended from three different unaffected fathers and an unaffected mother.