The detection of germline mutations in BRCA1 and BRCA2 is essential to the formulation of clinical management strategies, and in Brazil, there is limited access to these services, mainly due to the costs/availability of genetic testing. Aiming at the identification of recurrent mutations that could be included in a low-cost mutation panel, used as a first screening approach, we compiled the testing reports of 649 probands with pathogenic/likely pathogenic variants referred to 28 public and private health care centers distributed across 11 Brazilian States. Overall, 126 and 103 distinct mutations were identified in BRCA1 and BRCA2, respectively. Twenty-six novel variants were reported from both genes, and BRCA2 showed higher mutational heterogeneity. Some recurrent mutations were reported exclusively in certain geographic regions, suggesting a founder effect. Our findings confirm that there is significant molecular heterogeneity in these genes among Brazilian carriers, while also suggesting that this heterogeneity precludes the use of screening protocols that include recurrent mutation testing only. This is the first study to show that profiles of recurrent mutations may be unique to different Brazilian regions. These data should be explored in larger regional cohorts to determine if screening with a panel of recurrent mutations would be effective.

Cancer risk is highly variable in carriers of the common TP53-R337H founder allele, possibly due to the influence of modifier genes. Whole-genome sequencing identified a variant in the tumor suppressor XAF1 (E134*/Glu134Ter/rs146752602) in a subset of R337H carriers. Haplotype-defining variants were verified in 203 patients with cancer, 582 relatives, and 42,438 newborns. The compound mutant haplotype was enriched in patients with cancer, conferring risk for sarcoma (P = 0.003) and subsequent malignancies (P = 0.006). Functional analyses demonstrated that wild-type XAF1 enhances transactivation of wild-type and hypomorphic TP53 variants, whereas XAF1-E134* is markedly attenuated in this activity. We propose that cosegregation of XAF1-E134* and TP53-R337H mutations leads to a more aggressive cancer phenotype than TP53-R337H alone, with implications for genetic counseling and clinical management of hypomorphic TP53 mutant carriers.

IntroductionNo published clinical trial data are available to inform the use of enzyme replacement therapy (ERT) in patients with the severe (neuropathic) phenotype of mucopolysaccharidosis II (MPS II). Current guidelines recommend ERT administered intravenously be used on a trial basis in this population.Aims/methodsA retrospective chart review was conducted at five international centers for this case series of 22 patients with neuropathic MPS II who received intravenous idursulfase 0.5 mg/kg weekly for at least 2 consecutive years. We collected data about urinary glycosaminoglycan levels, adverse events, and the following somatic signs/symptoms: skeletal disease, joint range of motion, liver/spleen size, respiratory infections, cardiac disease, diarrhea, skin/hair texture, and hospitalizations.ResultsThe age at diagnosis was 2 months to 5 years, and the age at idursulfase initiation was between 18 months and 21 years. One of 22 patients experienced improvements in seven somatic signs/symptoms; 17/22 experienced improvements in five to six somatic signs/symptoms; and 4/22 experienced improvements in four somatic signs/symptoms. None experienced fewer than four improvements. No new safety concerns arose. Infusion-related reactions were experienced by 4/22 patients but were successfully managed using accepted strategies.ConclusionsLong-term treatment with idursulfase was associated with improvements in somatic manifestations in this case series of patients with neuropathic MPS II. The family and medical team should maintain open lines of communication to make treatment decisions that take into consideration the benefits and limitations of ERT in this population.Electronic supplementary materialThe online version of this article (doi:10.1007/s10545-014-9686-7) contains supplementary material, which is available to authorized users.

BackgroundGermline pathogenic variants in BRCA1 and BRCA2 (BRCA) are the main cause of Hereditary Breast and Ovarian Cancer syndrome (HBOC).MethodsIn this study we evaluated the mutational profile and prevalence of BRCA pathogenic/likely pathogenic variants among probands fulfilling the NCCN HBOC testing criteria. We characterized the clinical profile of these individuals and explored the performance of international testing criteria.ResultsA pathogenic/likely pathogenic variant was detected in 19.1% of 418 probands, including seven novel frameshift variants. Variants of uncertain significance were found in 5.7% of individuals. We evaluated 50 testing criteria and mutation probability algorithms. There was a significant odds-ratio (OR) for mutation prediction (p ≤ 0.05) for 25 criteria; 14 of these had p ≤ 0.001. Using a cutoff point of four criteria, the sensitivity is 83.8%, and the specificity is 53.5% for being a carrier. The prevalence of pathogenic/likely pathogenic variants for each criterion ranged from 22.1% to 55.6%, and criteria with the highest ORs were those related to triple-negative breast cancer or ovarian cancer.ConclusionsThis is the largest study of comprehensive BRCA testing among Brazilians to date, and the first to analyze clinical criteria for genetic testing. Several criteria that are not included in the NCCN achieved a higher predictive value. Identification of the most informative criteria for each population will assist in the development of a rational approach to genetic testing, and will enable the prioritization of high-risk individuals as a first step towards offering testing in low-income countries.

Warm antibody autoimmune hemolytic anemia is usually associated with extravascular hemolysis. We report a case of a 42 year old man with sustained and moderately severe warm antibody autoimmune hemolytic anemia, hemoglobinuria, hemosiderinuria, and acute kidney injury (AKI). We demonstrate marked induction of heme oxygenase-1 (HO-1) and increased expression of ferritin in renal tubules along with increased deposition of iron in renal proximal tubules. These findings in this clinical case thus recapitulate those observed in experimental models of heme protein-induced kidney injury in which a coupled induction of HO-1 and ferritin occurs in the kidney. We discuss the pathobiologic significance of these findings and suggest that this linked response confers cytoprotection to the kidney exposed to hemoglobin and mitigates the severity of acute kidney injury that may otherwise occur. Finally, this case report documents that nephrotic range proteinuria can occur in autoimmune hemolytic anemia complicated by hemoglobinuria.

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IntroductionThe association between the BTD genotype and biochemical phenotype [profound biotinidase deficiency (BD), partial BD or heterozygous activity] is not always consistent. This study aimed to investigate the genotype-biochemical phenotype association in patients with low biotinidase activity.MethodsAll exons, the 5'UTR and the promoter of the BTD gene were sequenced in 72 Brazilian individuals who exhibited low biotinidase activity. For each patient, the expected biochemical phenotype based on the known genotype was compared with the observed biochemical phenotype. Additional non-genetic factors that could affect the biotinidase activity were also analysed.ResultsMost individuals were identified by neonatal screening (n = 66/72). When consecutive results for the same patient were compared, age, prematurity and neonatal jaundice appeared to affect the level of biotinidase activity. The biochemical phenotype at the time of the second blood collection changed in 11/22 patients compared to results from the first sample. Three novel variants were found: c.1337T>C (p.L446P), c.1466A>G (p.N489S) and c.962G>A (p.W321*). Some patients with the same genotype presented different biochemical phenotypes. The expected and observed biochemical phenotypes agreed in 68.5% of cases (concordant patients). The non-coding variants c.-183G>A, c.-315A>G and c.-514C>T were present in heterozygosis in 5/17 discordant patients. In addition, c.-183G>A and c.-514C>T were also present in 10/37 concordant patients.ConclusionsThe variants found in the promoter region do not appear to have a strong impact on biotinidase activity. Since there is a disparity between the BTD genotype and biochemical phenotype, and biotinidase activity may be affected by both genetic and non-genetic factors, we suggest that the diagnosis of BD should be based on more than one measurement of plasma biotinidase activity. DNA analysis can be of additional relevance to differentiate between partial BD and heterozygosity.

The mucopolysaccharidoses (MPS) are a group of diseases arising from one of eleven different enzyme defects, each one affecting one single step of the degradation pathway of glycosamynoglycans. Several developments in the understanding of the MPS have occurred since the first clinical report about their occurrence in 1917: the nature of the storage product was recognized, a useful biomarker (mucopolysacchariduria) was developed, the enzyme defects became identified, and the gene defects were elucidated. The first successful treatment for MPS diseases was bone marrow transplantation, which was introduced for the therapy in 1980. Over the last decade, a whole new set of therapeutic approaches have become available or are currently in development to address MPS. Intravenous enzyme replacement therapy, already approved for MPS I, II, and VI, will possibly be available for MPS IVA and for MPS VII within the next few years. Intrathecal enzyme replacement therapy (tested in animals and already reported in a few patients) may become a tool to treat or prevent the central nervous system (CNS) manifestations which occur in several MPS. Substrate inhibition therapy using small molecules which cross the blood-brain barrier is also being tested for MPS types with CNS manifestations. In vitro studies point out that chaperones may also be of therapeutic value when the main cause is protein misfolding and retention at the endoplasmic reticulum. Stopcodon read-through strategy has been tried in preclinical studies with MPS models caused by nonsense mutations. Preclinical studies assessing gene therapy also show quite encouraging results, and this modality of treatment is now moving toward clinical development. The use of neural stem cells in MPS types which have CNS involvement is also promising. It is important to point out that MPS diseases are hard to treat, and demand specific therapies with a broad range of supportive measures. An additional challenge arises from the high cost of these technology intensive approaches, and this needs to be addressed if the treatments are to become widely available. Finally, since there is evidence that early diagnosis followed by early treatment considerably improves the health outcomes for these patients, newborn screening is becoming increasingly important for the early diagnosis of affected patients.