Spinocerebellar ataxia type 2 has multiple ancestral origins

INTRODUCTION

Spinocerebellar ataxia type 2 (SCA2) is a dominant neurodegenerative disorder due to expansions of a CAG repeat tract (CAGexp) at the ATXN2 gene. Previous studies found only one ancestral haplotype worldwide, with a C allele at rs695871. This homogeneity was unexpected, given the severe anticipations related to SCA2. We aimed to describe informative ancestral haplotypes found in South American SCA2 families.

METHODS

Seventy-seven SCA2 index cases were recruited from Brazil, Peru, and Uruguay; 263 normal chromosomes were used as controls. The SNPs rs9300319, rs3809274, rs695871, rs1236900 and rs593226, and the STRs D12S1329, D12S1333, D12S1672 and D12S1332, were used to reconstruct haplotypes.

RESULTS

Eleven ancestral haplotypes were found in SCA2 families. The most frequent ones were A-G-C-C-C (46.7 % of families), G-C-C-C-C (24.6 %) and A-C-C-C-C (10.3 %) and their mean (sd) CAGexp were 41.68 (3.55), 40.42 (4.11) and 45.67 (9.70) (p = 0.055), respectively. In contrast, the mean (sd) CAG lengths at normal alleles grouped per haplotypes G-C-G-A-T, A-G-C-C-C and G-C-C-C-C were 22.97 (3.93), 23.85 (3.59), and 30.81 (4.27) (p < 0.001), respectively. The other SCA2 haplotypes were rare: among them, a G-C-G-A-T lineage was found, evidencing a G allele in rs695871.

CONCLUSION

We identified several distinct ancestral haplotypes in SCA2 families, including an unexpected lineage with a G allele at rs695871, a variation never found in hundreds of SCA2 patients studied worldwide. SCA2 has multiple origins in South America, and more studies should be done in other regions of the world.

An Exploratory Survey on the Care for Ataxic Patients in the American Continents and the Caribbean

Little is known about access of rare disease carriers to health care. To increase this knowledge, the Pan American Hereditary Ataxia Network (PAHAN) conducted an exploratory survey about care for hereditary ataxias in American continents and the Caribbean. A questionnaire was sent to health professionals about the hereditary ataxias identified; access to care; and local teaching and research. The number of ataxics under current care per 100,000 inhabitants was subtracted from the expected overall prevalence of 6/100,000, to estimate the prevalence of uncovered ataxic patients. Local Human Development Indexes (HDI) were used to measure socio-economic factors. Twenty-six sites participated. Twelve sites had very high, 13 had high, and one site had medium HDI. Participants reported on 2239 and 602 patients with spinocerebellar ataxias and recessive forms under current care. The number of patients under current care per inhabitants varied between 0.14 and 12/100,000. The estimated prevalence of uncovered ataxic patients was inversely proportional to HDIs (rho = 0.665, p = 0.003). Access to diagnosis, pre-symptomatic tests, and rehabilitation were associated with HDIs. More and better molecular diagnostic tools, protocols and guidelines, and professional training for ataxia care were the top priorities common to all respondents. Evidence of inequalities was confirmed. Lower HDIs were associated with high potential numbers of uncovered ataxic subjects, and with lack of molecular diagnosis, pre-symptomatic testing, and rehabilitation. More and better diagnostic tools, guidelines, and professional training were priorities to all sites. PAHAN consortium might help with the last two tasks.

Neurological Phenotypes of IRF2BPL Gene Variants: A Report of Four Novel Variants

IRF2BPL gene variants have recently been associated to developmental disability and epilepsy in children and movement disorders in adults. So far, only few cases have been reported; here we present four novel cases identified by exome sequencing, while investigating developmental delay, adult-onset cerebellar ataxia or regression.

Diverse mutational spectrum in the 13q14 chromosomal region in a Brazilian cohort of retinoblastoma

Retinoblastoma is a rare childhood tumor caused by the inactivation of both copies of the RB1 gene. Early diagnosis and identification of heritable RB1 mutation carriers can improve the disease outcome and management via genetic counseling. We used the Multiplex Ligation-dependent Probe Amplification (MLPA) method to analyze the RB1 gene and flanking regions in blood samples from 159 retinoblastoma patients previously negative for RB1 point mutations via Sanger sequencing. We detected a wide spectrum of germline chromosomal alterations, ranging from partial loss or duplication of RB1 to large deletions spanning RB1 and adjacent genes. Mutations were validated via karyotyping, fluorescent in situ hybridization (FISH), SNP-arrays (Single Nucleotide Polymorphism-arrays) and/or quantitative relative real-time PCR. Patients with leukocoria as a presenting symptom showed reduced death rate (p = 0.013) and this sign occurred more frequently among carriers of two breakpoints within RB1 (p = 0.05). All unilateral cases presented both breakpoints outside of RB1 (p = 0.0075). Patients with one breakpoint within RB1 were diagnosed at earlier ages (p = 0.017). Our findings characterize the mutational spectrum of a Brazilian cohort of retinoblastoma patients and point to a possible relationship between the mutation breakpoint location and tumor outcome, contributing to a better prospect of the genotype/phenotype correlation and adding to the wide diversity of germline mutations involving RB1 and adjacent regions in retinoblastoma.

New drug candidates for osteosarcoma: Drug repurposing based on gene expression signature

Osteosarcoma (OS) is an aggressive bone malignancy and the third most common cancer in adolescence. Since the late 1970s, OS therapy and prognosis had only modest improvements, making it appealing to explore new tools that could help ameliorate the treatment. We present a meta-analysis of the gene expression signature of primary OS, and propose small molecules that could reverse this signature. The meta-analysis was performed using GEO microarray series. We first compared gene expression from eleven primary OS against osteoblasts to obtain the differentially expressed genes (DEGs). We later filtered those DEGs by verifying which ones had a concordant direction of differential expression in a validation group of 82 OS samples versus 30 bone marrow mesenchymal stem cells (BM-MSC) samples. A final gene expression signature of 266 genes (98 up and 168 down regulated) was obtained. The L1000CDS² engine was used for drug repurposing. The top molecules predicted to reverse the signature were afatinib (PubChem CID 10184653), BRD-K95196255 (PubChem CID 3242434), DG-041 (PubChem CID 11296282) and CA-074 Me (PubChem CID 23760717). Afatinib (Gilotrif™) is currently used for metastatic non-small-cell lung cancer with EGFR mutations, and in vitro evidence shows antineoplastic potential in OS cells. The other three molecules have reports of antineoplastic effects, but are not currently FDA-approved. Further studies are necessary to establish the potential of these drugs in OS treatment. We believe our results can be an important contribution for the investigation of new therapeutic genetic targets and for selecting new drugs to be tested for OS.

Free carnitine and branched chain amino acids are not good biomarkers in Huntington's disease

BACKGROUND

Huntington's disease (HD), caused by an expanded CAG repeat at HTT, has no treatment, and biomarkers are needed for future clinical trials.

OBJECTIVE

The objective of this study was to verify if free carnitine and branched chain amino acids levels behave as potential biomarkers in HD.

METHODS

Symptomatic and asymptomatic HD carriers and controls were recruited. Age, sex, body mass index (BMI), age of onset, disease duration, UHDRS scores, and expanded CAG tract were obtained; valine, leucine, isoleucine, and free carnitine were measured. Baseline and longitudinal analysis were performed.

RESULTS

Seventy-four symptomatic carriers, 20 asymptomatic carriers, and 22 non-carriers were included. At baseline, valine levels were reduced in symptomatic and asymptomatic HD carriers when compared to non-carriers. No difference in free carnitine or isoleucine+leucine levels were observed between groups. BMI of symptomatic individuals was lower than those of non-carriers. Valine levels correlated with BMI. Follow-up evaluation was performed in 43 symptomatic individuals. UHDRS total motor score increased 4.8 points/year on average. No significant reductions in BMI or valine were observed, whereas free carnitine and isoleucine+leucine levels increased.

CONCLUSIONS

Although valine levels were lower in HD carriers and were related to BMI losses observed in pre-symptomatic individuals, none of these metabolites seem to be biomarkers for HD.

Cancer-related worry and risk perception in Brazilian individuals seeking genetic counseling for hereditary breast cancer

In Brazil, the population in general has little knowledge about genetic risks, as well as regarding the role and importance of the Cancer Genetic Counseling (CGC). The goal of this study was to evaluate cancer-related worry and cancer risk perception during CGC sessions in Brazilian women at-risk for hereditary breast cancer. This study was performed in 264 individuals seeking CGC for hereditary breast cancer. Both cancer-affected and unaffected individuals were included. As results, individuals with and without cancer reported different motivations for seeking CGC and undergoing genetic testing. A correlation was observed between age at the first CGC session and age at which the closest relative was diagnosed with cancer. Multivariate analysis showed that educational level, cancer risk discussion within the family, and number of deaths by cancer among first-degree relatives influenced positively the cancer risk perception. In conclusion, the results of this study indicate that cancer-related worry and cancer risk perception are significant aspects of morbidity in individuals seeking CGC, whether they are cancer-affected or unaffected. CGC has an important role in health education and cancer prevention for its potential of promoting an accurate perception of the risk.

Minimal prevalence of Huntington's disease in the South of Brazil and instability of the expanded CAG tract during intergenerational transmissions

Huntington’s disease (HD) is due to dominant expansions of the CAG repeat of the HTT gene. Meiotic instability of the (CAG)_n might impact the disorder frequency. We report on HD minimal prevalence in Rio Grande do Sul (RS) state, Brazil, and on intergenerational instability of the (CAG)_n in HD families. Symptomatic and at-risk subjects from 179 HD families were ascertained between 2013 and 2016. Clinical, molecular and family history data were obtained. Expanded (CAG)_n length differences between parent and child (delta-expanded-(CAG)_n) were calculated. Effect of parental age on the (CAG)_n instability upon transmission was inferred by correlating delta-expanded-(CAG)_n between siblings to their age differences. HD minimal prevalence in RS state was estimated as 1.85:100,000 inhabitants. Alleles with (CAG)_27-35 were found on 21/384 non-disease associated chromosomes (5.5%); among 253 expanded alleles, four (1.6%) were within reduced penetrance range with (CAG)_36-39. In 32 direct transmissions, mean instability was larger among paternal than maternal transmissions. In direct transmissions and in 51 sibling pairs, parental age at the time of child birth were not correlated with delta-expanded-(CAG)_n. Briefly, HD prevalence in RS state was lower than those reported for European populations. Expanded (CAG)_n transmissions were unstable and not associated to parental age.

Screening and characterization of BRCA2 c.156_157insAlu in Brazil: Results from 1380 individuals from the South and Southeast

Portuguese immigration to Brazil occurred in several waves and greatly contributed to the genetic composition of current Brazilian population. In this study, we evaluated the frequency of a Portuguese founder Alu insertion in BRCA2 exon 3 (c.156_157insAlu) among individuals fulfilling Hereditary Breast and Ovarian Cancer (HBOC) syndrome criteria in 1,380 unrelated families originated from three distinct Brazilian States. We identified the c.156_157insAlu BRCA2 mutation in nine (9/1,380; 0.65%) probands analised. In carrier probands, European ancestry had the highest proportion (80%), followed by the African (10%) and Amerindian and in most families with the rearrangement, haplotype analyses were compatible with the Portuguese ancestral haplotype. In conclusion, the present study reports a low albeit relevant frequency of the Portuguese BRCA2 founder mutation c.156_157insAlu in Brazilian patients at-risk for HBOC Brazilian population.

The progression rate of spinocerebellar ataxia type 2 changes with stage of disease

Background

Spinocerebellar ataxia type 2 (SCA2) affects several neurological structures, giving rise to multiple symptoms. However, only the natural history of ataxia is well known, as measured during the study duration. We aimed to describe the progression rate of ataxia, by the Scale for the Assessment and Rating of Ataxia (SARA), as well as the progression rate of the overall neurological picture, by the Neurological Examination Score for Spinocerebellar Ataxias (NESSCA), and not only during the study duration but also in a disease duration model. Comparisons between these models might allow us to explore whether progression is linear during the disease duration in SCA2; and to look for potential modifiers.

Results

Eighty–eight evaluations were prospectively done on 49 symptomatic subjects; on average (SD), study duration and disease duration models covered 13 (2.16) months and 14 (6.66) years of individuals’ life, respectively. SARA progressed 1.75 (CI 95%: 0.92–2.57) versus 0.79 (95% CI 0.45 to 1.14) points/year in the study duration and disease duration models. NESSCA progressed 1.45 (CI 95%: 0.74–2.16) versus 0.41 (95% CI 0.24 to 0.59) points/year in the same models. In order to explain these discrepancies, the progression rates of the study duration model were plotted against disease duration. Then an acceleration was detected after 10 years of disease duration: SARA scores progressed 0.35 before and 2.45 points/year after this deadline (p = 0.013). Age at onset, mutation severity, and presence of amyotrophy, parkinsonism, dystonic manifestations and cognitive decline at baseline did not influence the rate of disease progression.

Conclusions

NESSCA and SARA progression rates were not constant during disease duration in SCA2: early phases of disease were associated with slower progressions. Modelling of future clinical trials on SCA2 should take this phenomenon into account, since disease duration might impact on inclusion criteria, sample size, and study duration. Our database is available online and accessible to future studies aimed to compare the present data with other cohorts.

Electronic supplementary material

The online version of this article (10.1186/s13023-017-0725-y) contains supplementary material, which is available to authorized users.

TP53 and CDKN1A mutation analysis in families with Li-Fraumeni and Li-Fraumeni like syndromes

Li-Fraumeni and Li-Fraumeni like syndromes (LFS/LFL) represent rare cancer-prone conditions associated mostly with sarcomas, breast cancer, brain tumors, and adrenocortical carcinomas. TP53 germline mutations are present in up to 80 % of families with classic Li-Fraumeni syndrome, and in 20-60 % of families with Li-Fraumeni like phenotypes. The frequency of LFS/LFL families with no TP53 mutations detected suggests the involvement of other genes in the syndrome. In this study, we searched for mutations in TP53 in 39 probands from families with criteria for LFS/LFL. We also searched for mutations in the gene encoding the main mediator of p53 in cell cycle arrest, CDKN1A/p21, in all patients with no mutations in TP53. Eight probands carried germline disease-causing mutations in TP53: six missense mutations and two partial gene deletions. No mutations in CDKN1A coding region were detected. TP53 partial deletions in our cohort represented 25 % (2/8) of the mutations found, a much higher frequency than usually reported, emphasizing the need to search for TP53 rearrangements in patients with LFS/LFL phenotypes. Two benign tumors were detected in two TP53 mutation carriers: an adrenocortical adenoma and a neurofibroma, which raises a question about the possible implication of TP53 mutations on the development of such lesions.

Prevalence of Café-au-Lait Spots in children with solid tumors

Cafe-au-lait maculae (CALM) are frequently observed in humans, and usually are present as a solitary spot. Multiple CALMs are present in a smaller fraction of the population and are usually associated with other congenital anomalies as part of many syndromes. Most of these syndromes carry an increased risk of cancer development. Previous studies have indicated that minor congenital anomalies may be more prevalent in children with cancer. We investigated the prevalence of CALMs in two samples of Brazilian patients with childhood solid tumors, totaling 307 individuals. Additionally, 176 school children without diagnosis of cancer, or of a cancer predisposing syndrome, were investigated for the presence of CALMs. The prevalence of solitary CALM was similar in both study groups (18% and 19%) and also in the group of children without cancer. Multiple CALMs were more frequently observed in one of the study groups (Z = 2.1). However, when both groups were analyzed together, the significance disappeared (Z = 1.5). The additional morphological abnormalities in children with multiple CALMs were analyzed and compared to the findings observed in the literature. The nosologic entities associated with CALMs are reviewed.

BRCA1 and BRCA2 rearrangements in Brazilian individuals with Hereditary Breast and Ovarian Cancer Syndrome

Approximately 5-10% of breast cancers are caused by germline mutations in high penetrance predisposition genes. Among these, BRCA1 and BRCA2, which are associated with the Hereditary Breast and Ovarian Cancer (HBOC) syndrome, are the most frequently affected genes. Recent studies confirm that gene rearrangements, especially in BRCA1, are responsible for a significant proportion of mutations in certain populations. In this study we determined the prevalence of BRCA rearrangements in 145 unrelated Brazilian individuals at risk for HBOC syndrome who had not been previously tested for BRCA mutations. Using Multiplex Ligation-dependent Probe Amplification (MLPA) and a specific PCR-based protocol to identify a Portuguese founder BRCA2 mutation, we identified two (1,4%) individuals with germline BRCA1 rearrangements (c.547+240_5193+178del and c.4675+467_5075-990del) and three probands with the c.156_157insAlu founder BRCA2 rearrangement. Furthermore, two families with false positive MLPA results were shown to carry a deleterious point mutation at the probe binding site. This study comprises the largest Brazilian series of HBOC families tested for BRCA1 and BRCA2 rearrangements to date and includes patients from three regions of the country. The overall observed rearrangement frequency of 3.44% indicates that rearrangements are relatively uncommon in the admixed population of Brazil.

Array CGH Analysis of Paired Blood and Tumor Samples from Patients with Sporadic Wilms Tumor

Wilms tumor (WT), the most common cancer of the kidney in infants and children, has a complex etiology that is still poorly understood. Identification of genomic copy number variants (CNV) in tumor genomes provides a better understanding of cancer development which may be useful for diagnosis and therapeutic targets. In paired blood and tumor DNA samples from 14 patients with sporadic WT, analyzed by aCGH, 22% of chromosome abnormalities were novel. All constitutional alterations identified in blood were segmental (in 28.6% of patients) and were also present in the paired tumor samples. Two segmental gains (2p21 and 20q13.3) and one loss (19q13.31) present in blood had not been previously described in WT. We also describe, for the first time, a small, constitutive partial gain of 3p22.1 comprising 2 exons of CTNNB1, a gene associated to WT. Among somatic alterations, novel structural chromosomal abnormalities were found, like gain of 19p13.3 and 20p12.3, and losses of 2p16.1-p15, 4q32.5-q35.1, 4q35.2-q28.1 and 19p13.3. Candidate genes included in these regions might be constitutively (SIX3, SALL4) or somatically (NEK1, PIAS4, BMP2) operational in the development and progression of WT. To our knowledge this is the first report of CNV in paired blood and tumor samples in sporadic WT.

Analysis of pre-test interviews in a cohort of Brazilian patients with movement disorders

Spinocerebellar ataxias and Huntington disease are heritable, adult onset, neurodegenerative disorders of movement. Both are autosomal dominant and caused by expansions in trinucleotide sequences in several genes. Because these expansions are associated with an almost complete penetrance, genetic tests are available at the diagnostic and predictive level. In this study, we describe the expectations and issues raised during pre-test interviews for genetic counselling for these diseases. Data from pre-test interviews with 97 patients and at-risk relatives for spinocerebellar ataxia (SCA) or Huntington disease was comprised of close-ended questions (demographics, personal and current disease history) and open-ended questions, where individuals were asked to describe their hopes and expectations on the genetic counselling evaluation and also their degree of knowledge about genetics and medical genetics. Amongst the main expectations identified in patients and at-risk relatives, issues related to the aetiological diagnosis and/or disclosure of the at-risk status were those most frequently mentioned (57 %). Improvement in quality of life was another identified issue (17 %). Interestingly, the issue of inheritance/transmission was identified as the main expectation by a minority of individuals (3 %). Pre-test interviews are valuable tools to identify issues raised by consultands and promote a better communication between the patient, family and the genetic counselling team.

Magnesium sulfate affords protection against oxidative damage during severe preeclampsia

INTRODUCTION

MgSO4 is the drug of choice to prevent seizures in preeclamptic pregnant women, but its mechanism of action at the molecular level remains an enigma. In previous works, we found that treating preeclamptic women with MgSO4 reduces the lipid peroxidation of their red blood cell membranes to normal levels and leads to a significant reduction in the osmotic fragility of the red blood cells that is increased during preeclampsia. In addition, the increase in lipid peroxidation of red cell membranes induced by the Fenton reaction does not occur when MgSO4 is present.

METHODS

The antioxidant protection of MgSO4 was evaluated in UV-C-treated red blood cell ghosts and syncytiotrophoblast plasma membranes by measuring their level of lipid peroxidation. The interaction of MgSO4 with free radicals was assessed for its association with the galvinoxyl radical, the quenching of H2O2-induced chemiluminescence and its effect on sensitized peroxidation of linoleic acid.

RESULTS

a) MgSO4 protected red blood cell ghosts and the syncytiotrophoblast plasma membranes of normotensive pregnant women against lipid peroxidation induced by UV-C irradiation. b) MgSO4 does not seem to scavenge the galvinoxyl free radical. c) The quenching of the H2O2-enhanced luminol chemiluminescence is increased by the presence of MgSO4. d) The peroxidation of linoleic acid is significantly blocked by MgSO4.

DISCUSSION

MgSO4 may provide protection against oxidative damage of plasma membranes through interactions with alkyl radicals.

Spinocerebellar ataxias in Brazil--frequencies and modulating effects of related genes

This study describes the frequency of spinocerebellar ataxias and of CAG repeats range in different geographical regions of Brazil, and explores the hypothetical role of normal CAG repeats at ATXN1, ATXN2, ATXN3, CACNA1A, and ATXN7 genes on age at onset and on neurological findings. Patients with symptoms and family history compatible with a SCA were recruited in 11 cities of the country; clinical data and DNA samples were collected. Capillary electrophoresis was performed to detect CAG lengths at SCA1, SCA2, SCA3/MJD, SCA6, SCA7, SCA12, SCA17, and DRPLA associated genes, and a repeat primed PCR was used to detect ATTCT expansions at SCA10 gene. Five hundred forty-four patients (359 families) were included. There were 214 SCA3/MJD families (59.6 %), 28 SCA2 (7.8 %), 20 SCA7 (5.6 %), 15 SCA1 (4.2 %), 12 SCA10 (3.3 %), 5 SCA6 (1.4 %), and 65 families without a molecular diagnosis (18.1 %). Divergent rates of SCA3/MJD, SCA2, and SCA7 were seen in regions with different ethnic backgrounds. 64.7 % of our SCA10 patients presented seizures. Among SCA2 patients, longer ATXN3 CAG alleles were associated with earlier ages at onset (p < 0.036, linear regression). A portrait of SCAs in Brazil was obtained, where variation in frequencies seemed to parallel ethnic differences. New potential interactions between some SCA-related genes were presented.

Segmental uniparental isodisomy of chromosome 6 causing transient diabetes mellitus and merosin-deficient congenital muscular dystrophy

Segmental uniparental isodisomy (iUPD) is a rare genetic event that may cause aberrant expression of imprinted genes, and reduction to homozygosity of a recessive mutation. Transient neonatal diabetes mellitus (TNDM) is typically caused by imprinting aberrations in chromosome 6q24 TNDM differentially-methylated region (DMR). Approximately, 15.12 Mb upstream in 6q22-q23 is located LAMA2, the gene responsible of merosin-deficient congenital muscular dystrophy type 1A (MDC1A). We investigated a patient diagnosed both with TNDM and MDC1A, born from a twin dichorionic discordant pregnancy. Parents are first-degree cousins. Methylation sensitive-PCR of the imprinted 6q24 TNDM CpG island showed only the non-methylated (paternal) allele. Microsatellite markers and SNP array profiling disclosed normal biparental inheritance at 6p and a segmental paternal iUPD, between 6q22.33 and 6q27. Sequencing of LAMA2 exons showed a homozygous frameshift mutation, c.7490_7493dupAAGA, which predicts p.Asp2498GlufsX4, in exon 54. Her father, but not her mother, was a carrier of the mutation. While segmental paternal iUPD6 causing TNDM was reported twice, there are no previous reports of MDC1A caused by this event. This is a child with two genetic disorders, yet neither is caused by the parental consanguinity, which reinforces the importance of considering different etiological mechanisms in the genetic clinic.

Prevalence and impact of founder mutations in hereditary breast cancer in Latin America

Approximately 10% of all cancers are considered hereditary and are primarily caused by germline, high penetrance mutations in cancer predisposition genes. Although most cancer predisposition genes are considered molecularly heterogeneous, displaying hundreds of different disease-causing sequence alterations, founder mutations have been identified in certain populations. In some Latin American countries, founder mutations associated with increased risk of breast and other cancers have been described. This is particularly interesting considering that in most of these countries, populations are highly admixed with genetic contributions from native populations and from the in-flux of several distinct populations of immigrants. In this article, we present a review of the scientific literature on the subject and describe current data available on founder mutations described in the most common breast cancer predisposition genes: BRCA1, BRCA2 and TP53.

Molecular analysis of holoprosencephaly in South America

Holoprosencephaly (HPE) is a spectrum of brain and facial malformations primarily reflecting genetic factors, such as chromosomal abnormalities and gene mutations. Here, we present a clinical and molecular analysis of 195 probands with HPE or microforms; approximately 72% of the patients were derived from the Latin American Collaborative Study of Congenital Malformations (ECLAMC), and 82% of the patients were newborns. Alobar HPE was the predominant brain defect in almost all facial defect categories, except for patients without oral cleft and median or lateral oral clefts. Ethmocephaly, cebocephaly, and premaxillary agenesis were primarily observed among female patients. Premaxillary agenesis occurred in six of the nine diabetic mothers. Recurrence of HPE or microform was approximately 19%. The frequency of microdeletions, detected using Multiplex Ligation-dependant Probe Amplification (MLPA) was 17% in patients with a normal karyotype. Cytogenetics or QF-PCR analyses revealed chromosomal anomalies in 27% of the probands. Mutational analyses in genes SHH, ZIC2, SIX3 and TGIF were performed in 119 patients, revealing eight mutations in SHH, two mutations in SIX3 and two mutations in ZIC2. Thus, a detailed clinical description of new HPE cases with identified genetic anomalies might establish genotypic and phenotypic correlations and contribute to the development of additional strategies for the analysis of new cases.

Association of TP53 polymorphisms on the risk of Wilms tumor

BACKGROUND

Molecular factors influencing Wilms tumor (WT) development remain largely unknown. TP53 mutations seem to be restricted to the anaplastic WT subtype. However, TP53 polymorphisms do not have a defined role in the disease.

PROCEDURE

To assess the impact of TP53 mutations and polymorphisms (PIN2, PIN3, and PEX4) on risk of development, age at diagnosis, and survival in WT, we analyzed 46 blood DNA samples and 31 fresh tumor DNA samples from 52 patients with WT. Sequencing of TP53 exons 2-11 was performed.

RESULTS

Tumor DNA analysis revealed TP53 pathogenic missense mutations (p.V197M, p.R213Q, p.R248W, and p.R337C) in four samples (12.9%). Blood DNA samples revealed a novel intronic mutation, IVS2 + 37C > T, in one patient (2.2%). Bilaterality was associated with a twofold decrease in survival (P = 0.00037). Diffuse anaplasia also presented a lower survival probability compared to patients with non-anaplastic tumors, or with focal anaplasia (P = 0.045). Patients with a TP53 somatic mutation showed survival probability of 37.5% versus 85.0% for patients with no somatic mutations, although the difference was not statistically significant (P = 0.0706). PIN3 duplicated allele was associated with a 20-month later mean age at diagnosis (P = 0.0084). TP53 PEX4 C allele showed an increased risk for WT development (P = 0.0379). No relationship was found between survival and gender, age at diagnosis, or the less frequent alleles of PIN2, PIN3, and PEX4.

CONCLUSIONS

Our results demonstrate an association between PIN3 and age at diagnosis, as well as an association of PEX4 and risk of development of WT.

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

The aim of this study was to identify the relative frequency of Huntington's 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; R(2) 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.

Polymorphisms of CDKN1A gene and risk of retinoblastoma

Retinoblastoma (RB) is a malignant neoplasia that occurs mostly in children under 5 years. Recently, CDKN1A gene has been shown to be up-regulated in a context of loss of function of pRb. This gene encodes the p21 protein, which is the bona fide effector of p53. We hypothesized whether two putatively functional single nucleotide polymorphisms (SNPs) of CDKN1A (rs1801270 C>A and rs1059234 C>T) may influence the risk and/or survival of RB patients. We genotyped both SNPs in 141 RB patients and 120 unrelated healthy individuals. Statistical analyses consisted of chi-square (χ(2)), odds ratio (OR) and survival curves by Kaplan-Meier method. We found that patients who carry the genotype CA for rs1801270 and CT for rs1059234 were associated to an increased risk of RB [OR = 2.5, 95% confidence interval (CI) = 1.38-4.53], whereas patients with CC for both polymorphisms were associated to a lower risk of developing RB (OR = 0.43, 95% CI = 0.25-0.74). On the other hand, Kaplan-Meier curves did not show statistically significant differences in survival among the studied polymorphisms. We conclude that the minor alleles of rs1801270 and rs1059234 polymorphisms may act as risk factors for the development of RB in our sample.

SUMMARY

The minor alleles of polymorphisms rs1801270 C>A and rs1059234 C>T in CDKN1A (p21) gene may act as risk factors for the development of RB; however, they do not seem to influence overall survival.

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

BACKGROUND

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.

PROCEDURE

We genotyped rs2279744T>G and rs937283A>G in MDM2, and rs4252668T>C and rs116197192G>A in MDM4, in 104 unrelated RB patients and 104 controls. Sixty-month survival Kaplan-Meier curves and χ(2)-tests were performed for estimating the putative effect of MDM2 and MDM4 alleles on disease progression and survival of RB patients.

RESULTS

MDM2 rs2279744G was significantly more frequent in controls, indicating an apparently protective effect on RB development. However, survival of patients who carried a constitutional RB1 mutation was significantly lower with rs2279744TG or GG than with rs2279744TT. Presence of rs2279744G and a constitutional RB1 mutation was sixfold more frequent in the 0-12 month age group than other age groups at onset of symptoms (P = 0.0401). MDM4 rs4252668C was present at a significantly higher frequency in controls while the frequency of MDM4 rs116197192G was significantly higher in RB patients, suggesting that this allele might increase the risk of developing RB.

CONCLUSION

Our results indicate that MDM2 and MDM4 polymorphisms may influence development and/or survival in RB.

Identification and characterization of novel sequence variations in MECP2 gene in Rett syndrome patients

Rett syndrome (RS) is a neurodevelopmental disorder caused by mutations in MECP2 gene. Exons 2, 3, and 4, in addition to intronic and 3'UTR adjacent regions, were sequenced in 80 patients with RS. Twenty-nine sequence variations were detected in 49 patients, 34 (69.4%) patients with the classic form of RS, and 15 (30.6%) patients with atypical forms of RS. Thirteen of the 29 detected mutations represent novel sequence variations. Missense mutation T158M was the most commonly observed mutation, detected in nine patients (11.2%). Six hotspot pathogenic mutations (R133C, T158M, R168X, R255X, R270X, and R294X) were responsible for the phenotype in 26/80 patients (32.5%).

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 3.1x10(-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.

DNA extraction from fixed cytogenetic cell suspensions

We developed a procedure for DNA extraction from small volumes of fixed cell suspensions previously prepared for conventional cytogenetic analysis. Good quality DNA was isolated with a fast and simple protocol using DNAzol reagent. This provided suitable DNA for various types of molecular analyses, including polymerase chain reaction, restriction fragment length polymorphism, denaturing high-performance liquid chromatography, and direct sequencing. This technique provides sufficient material for such test, which are important for diagnosis of neoplastic diseases in pediatric patients.

Cancer genetic counseling in public health care hospitals: the experience of three Brazilian services

In Brazil, genetic counseling is usually available in university-affiliated medical genetics services located in tertiary centers that provide cancer diagnosis and treatment. The present study aims to describe the structure and characteristics of three cancer genetic services in Brazilian public health care hospitals and discuss alternatives for the identification and prevention of hereditary cancer syndromes in developing countries. The three services presented here are similar in their structure, routine procedures for cancer risk estimation and criteria for the indication of genetic testing. They all demand that genetic counseling be an essential part of the cancer risk evaluation process, before and after cancer predisposition testing. However, when high-risk patients are identified, all services describe difficulties in the access and continuity of genetic and medical services to the patient and his/her at-risk relatives. The services differ in the type of population served, reflecting distinct referral guidelines. This study emphasizes the importance of the creation of new cancer genetic services in other Brazilian regions and the necessity for establishing a collaborative network to facilitate the diagnosis and research of cancer genetic syndromes.

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.

A molecular study of first and second RB1 mutational hits in retinoblastoma patients

RB1 mutations accountable for biallelic inactivation are crucial events in the development of retinoblastoma because a first mutation (M1) predisposes to retinoblastoma while a second mutation (M2) is required for tumor development. Mutational analyses of this gene showed a wide spectrum of genetic alterations (single base substitutions, insertions, or deletions, as well as small and large deletions). The most frequent second hit in retinoblastoma patients is loss of heterozygosity (LOH) followed by promoter methylation. Molecular analyses of RB1 mutations were conducted in 36 patients (20 unilateral and 16 bilateral) using polymerase chain reaction-mediated single-strand conformation polymorphism (SSCP) analysis, sequencing, and LOH analysis. Sixty-four amplified fragments showing abnormal SSCP patterns were sequenced, and mutations were confirmed in five patients (13.89%). Four mutations were located at coding regions, and a fifth one was found at an exon-intron junction. Two mutations were C-->T transitions, two were small-length deletions, and one was a G-->A transition. A total of 47.05% patients showed LOH. In one patient, the parental origin of the mutated allele was detected: the allele retained in the tumor was the paternal one. This work helps to characterize the spectrum of mutations in the Brazilian population, and to confirm that formaldehyde-fixed paraffin tissue can provide valuable information on the RB1 status in retinoblastoma patients.

The TP53 mutation, R337H, is associated with Li-Fraumeni and Li-Fraumeni-like syndromes in Brazilian families

A TP53 germline mutation, R337H, has been previously described in children from southern Brazil with adrenocortical tumours but no documented familial history of other cancers. Here, we have screened for TP53 mutation 45 Brazilian unrelated individuals with family histories fulfilling the clinical definitions of Li-Fraumeni (LFS) or Li-Fraumeni-like (LFL) syndromes. Mutations were found in 13 patients (28.9%), including six (46.1%) R337H mutations, and four novel germline mutations (V173M, V197M, G244D and IVS6+1G>T). Families with the R337H mutation presented a wide spectrum of tumours, including breast cancers (30.4%), brain cancers (10.7%), soft tissue sarcomas (10.7%) and adrenocortical carcinomas (8.9%). Testing of 53 Brazilian subjects with no cancer history showed that R337H was not a common polymorphism in that population. Moreover, loss of heterozygocity with retention of the R337H allele was observed in a breast adenocarcinoma, supporting a role for this mutation in breast tumorigenesis. These results show that the TP53 R337H germline mutation predisposes to a larger spectrum of tumours, similar to the one reported for other TP53 mutations.

Identification of three novel RB1 mutations in Brazilian patients with retinoblastoma by "exon by exon" PCR mediated SSCP analysis

AIMS

To carry out a retrospective study, screening for mutations of the entire coding region of RB1 and adjacent intronic regions in patients with retinoblastoma.

METHODS

Mutation screening in DNA extracts of formalin fixed, paraffin wax embedded tissues of 28 patients using combined "exon by exon" polymerase chain reaction mediated single strand conformational polymorphism analysis, followed by DNA sequencing.

RESULTS

Eleven mutations were found in 10 patients. Ten mutations consisted of single base substitutions; 10 were localised in exonic regions (eight nonsense, one missense, and one frameshift) and another one in the intron-exon splicing region. Three novel mutations were identified: a 2 bp insertion in exon 2 (g.5506-5507insAG, R73fsX77), a G to A transition affecting the last invariant nucleotide of intron 13 (g.76429G>A), and a T to C transition in exon 20 (g.156795T>C, L688P). In addition, eight C to T transitions, resulting in stop codons, were found in five different CGA codons (g.64348C>T, g.76430C>T, g.78238C>T, g.78250C>T, and g.150037C>T). Although specific mutation hotspots have not been identified in the literature, eight of the 11 mutations occurred in CGA codons and seven fell within the E1A binding domains (codons 393-572 and 646-772), whereas five were of both types-in CGA codons within E1A binding domains.

CONCLUSIONS

CGA codons and E1A binding domains are apparently more frequent mutational targets and should be initially screened in patients with retinoblastoma. Paraffin wax embedded samples proved to be valuable sources of DNA for retrospective studies, providing useful information for genetic counselling.

Clinical, neuroimaging and cytogenetic findings in 20 patients with corpus callosum dysgenesis

Twenty children with corpus callosum agenesis or hypoplasia were evaluated under a standardized investigation protocol. Psychomotor retardation, seizures, and craniofacial anomalies were the most prominent findings. There were three cases of chromosomal anomalies, all of them representing trisomy of chromosome 8.

Clinical, neuroimaging and cytogenetic findings in 20 patients with corpus callosum dysgenesis

Twenty children with corpus callosum agenesis or hypoplasia were evaluated under a standardized investigation protocol. Psychomotor retardation, seizures, and craniofacial anomalies were the most prominent findings. There were three cases of chromosomal anomalies, all of them representing trisomy of chromosome 8.

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.

Analysis of the human Sonic Hedgehog coding and promoter regions in sacral agenesis, triphalangeal thumb, and mirror polydactyly

The human Sonic Hedgehog gene (SHH) is one of the vertebrate homologs related to the Drosophila segment polarity gene hedgehog. The entire coding and promoter region of the SHH gene, including 2 kb 5' of the transcriptional start site has been screened for mutations in families with autosomal dominant sacral agenesis and autosomal dominant triphalangeal thumb, two conditions previously known to be linked to 7q36. We have also studied the SHH gene in five families with mirror polydactyly associated with tibial hemimelia and in 51 unrelated patients with neural tube defects. Except for two sequence variants in exon 3, no mutations were found in these disease categories. OFF

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.

Autosomal dominant osteosclerosis type Stanescu: the third family

We describe a family with Stanescu osteosclerosis. The propositus and his mother were short and had cortical sclerosis of the long bones, deficient facial sinus development, cranial bone malformations, and normal intelligence. To the best of our knowledge, only two such families have been described previously. The autosomal dominant pattern of inheritance of this skeletal dysplasia is reinforced, as there are many other reportedly affected relatives, including the maternal grandfather, uncles, and aunts of the propositus. The findings of wormian bones and calcification of the falx, not previously described, may be added to the phenotype.

[Down Syndrome--a clinical, cytogenetic and epidemiologic analysis of 165 patients]

A clinical follow up of 165 Down Syndrome (DS) patients in an outpatient clinic programme at the Centro de Genética Médica (IFF - FIOCRUZ) was undertaken retrospectively. Clinical and laboratorial investigations were performed, such as cytogenetics and hematological analysis, thyroid hormones survey, abdominal ultrasound and cervical column X Rays. The clinical diagnosis of Down Syndrome was mostly performed during the first year of life, and 70% of all patients were under 4 years of age, being predominantly males. Trisomy 21 derived from non disjunction was found in 85% of the patients. The most common congenital malformation was cardiopathy (37.5%) and among all the clinical complications, repeated pneumonia could be evidenced in 30% of the patients, mainly during the first year of life. Leukopenia was observed in 14% of the patients and abdominal ultrasound scans allowed the early detection of biliary stones in 4.3% of the patients examined, a significative finding in the paediatric population. A prospective clinical programme aiming to anticipate the detection of clinical complications on at risk DS populations will fulfill its objectives and may act as a reducing factor in the infantile mortality rate.

Absent tibiae--polydactyly--triphalangeal thumbs with fibular dimelia: variable expression of the Werner (McKusick 188770) syndrome?

We report on a family in which the autosomal dominant Werner syndrome (WS) (MIM# 188770) affects ten members in three generations. Besides the absent tibiae the propositus had duplication of the fibulae. Possible pathogenetic mechanism is discussed.

CODAS syndrome: a new distinct MCA/MR syndrome with radiological changes of spondyloepiphyseal dysplasia. Another case report

We report on a young girl with psychomotor delay, cataracts, abnormally shaped teeth, malformed ears, and radiological findings of spondylo-epiphyseal dysplasia. The clinical picture resembles the CODAS syndrome described by Shebib et al. [Am J Med Genet 40: 88-93, 1991].

Further report of a patient with humeroradioulnar synostosis and hydronephrosis

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Limb deficiency with or without Möbius sequence in seven Brazilian children associated with misoprostol use in the first trimester of pregnancy

Misoprostol, a synthetic analog of prostaglandin, has been widely used in Brazil as an abortifacient. Abortion is illegal in Brazil. An uncertain number of these abortion attempts are unsuccessful and the pregnancy continues. We report on 7 patients whose mothers attempted to abort using this drug in the first trimester of gestation without success. The 7 patients presented with limb defects and in 4 of them a diagnosis of Möbius sequence was made.

RAPADILINO syndrome

We report on a boy with severe radial hypoplasia, absent thumbs and patellae, short stature, persistent diarrhea, slender nose and normal intelligence as another example of the RAPADILINO syndrome.