Germline heterozygous exons 8-11 pathogenic BARD1 gene deletion reported for the first time in a family with suspicion of a hereditary colorectal cancer syndrome: more than an incidental finding?

BACKGROUND: Colorectal cancer (CRC) is a highly prevalent disease in developed countries. Inherited Mendelian causes account for approximately 5% of CRC cases, with Lynch syndrome and familial adenomatous polyposis being the most prevalent forms. Scientific efforts are focused on the discovery of new candidate genes associated with CRC and new associations of phenotypes with well-established cancer-related genes. BRCA1-associated ring domain (BARD1) gene deleterious germline variants are associated with a moderate increase in the relative risk of breast cancer, but their association with other neoplasms, such as CRC, remains unclear. CASE PRESENTATION: We present the case of a 49-year-old male diagnosed with rectal adenocarcinoma whose maternal family fulfilled Amsterdam clinical criteria for Lynch syndrome. Genetic test confirmed the presence in heterozygosis of a germline pathogenic deletion of exons 8-11 in BARD1 gene. The predictive genetic study of the family revealed the presence of this pathogenic variant in his deceased cancer affected relatives, confirming co-segregation of the deletion with the disease. CONCLUSIONS: To the best of our knowledge, this is the first published work in which this BARD1 deletion is detected in a family with familial colorectal cancer type X (FCCTX) syndrome, in which the clinical criteria for Lynch syndrome without alteration of the DNA mismatch repair (MMR) system are fulfilled. Whether this incidental germline finding is the cause of familial colorectal aggregation remains to be elucidated in scientific forums. Patients should be carefully assessed in specific cancer genetic counseling units to account for hypothetical casual findings in other genes, in principle unrelated to the initial clinical suspicion, but with potential impact on their health.

[Familial endometrial adenocarcinoma: MSH6 variant of unknown significance in the presence of phenocopy, what should be done?] / Adenocarcinoma de endometrio en una familia: variante de significado incierto en MSH6 en presencia de fenocopia, ¿cómo resolverlo?

Endometrial cancer (EC) is the second most common tumor in women with Lynch syndrome, and can be its first manifestation. It may exhibit negative immunostaining for DNA mismatch-repair proteins and/or microsatellite instability. We present the case of a woman with EC in which a MSH6 variant of unknown significance was identified. To establish the pathogenicity of the variant, the family study was extended, identifying her healthy sister as a carrier while her aunt, with EC, was not. In the latter, the histopathology of a first tumor block did not identify the pathway of carcinogenesis, but its repetition in a second tumor block suggested the possibility of it being a phenocopy. The multidisciplinary approach in the study of this family allowed a correct diagnosis of the different adenocarcinomas, adequate family genetic counselling and the correct assignment of pathogenicity to a variant in MSH6.

RNAseq based transcriptomics study of SMCs from carotid atherosclerotic plaque: BMP2 and IDs proteins are crucial regulators of plaque stability.

Carotid artery atherosclerosis is a risk factor to develop cerebrovascular disease. Atheroma plaque can become instable and provoke a cerebrovascular event or else remain stable as asymptomatic type. The exact mechanism involved in plaque destabilization is not known but includes among other events smooth muscle cell (SMC) differentiation. The goal of this study was to perform thorough analysis of gene expression differences in SMCs isolated from carotid symptomatic versus asymptomatic plaques. Comparative transcriptomics analysis of SMCs based on RNAseq technology identified 67 significant differentially expressed genes and 143 significant differentially expressed isoforms in symptomatic SMCs compared with asymptomatic. 37 of top-scoring genes were further validated by digital PCR. Enrichment and network analysis shows that the gene expression pattern of SMCs from stable asymptomatic plaques is suggestive for an osteogenic phenotype, while that of SMCs from unstable symptomatic plaque correlates with a senescence-like phenotype. Osteogenic-like phenotype SMCs may positively affect carotid atheroma plaque through participation in plaque stabilization via bone formation processes. On the other hand, plaques containing senescence-like phenotype SMCs may be more prone to rupture. Our results substantiate an important role of SMCs in carotid atheroma plaque disruption.

Mutations in TrkA Causing Congenital Insensitivity to Pain with Anhidrosis (CIPA) Induce Misfolding, Aggregation, and Mutation-dependent Neurodegeneration by Dysfunction of the Autophagic Flux.

Congenital insensitivity to pain with anhidrosis (CIPA) is a rare autosomal recessive disorder characterized by insensitivity to noxious stimuli and variable intellectual disability (ID) due to mutations in the NTRK1 gene encoding the NGF receptor TrkA. To get an insight in the effect of NTRK1 mutations in the cognitive phenotype we biochemically characterized three TrkA mutations identified in children diagnosed of CIPA with variable ID. These mutations are located in different domains of the protein; L213P in the extracellular domain, Δ736 in the kinase domain, and C300stop in the extracellular domain, a new mutation causing CIPA diagnosed in a Spanish teenager. We found that TrkA mutations induce misfolding, retention in the endoplasmic reticulum (ER), and aggregation in a mutation-dependent manner. The distinct mutations are degraded with a different kinetics by different ER quality control mechanisms; although C300stop is rapidly disposed by autophagy, Δ736 degradation is sensitive to the proteasome and to autophagy inhibitors, and L213P is a long-lived protein refractory to degradation. In addition L213P enhances the formation of autophagic vesicles triggering an increase in the autophagic flux with deleterious consequences. Mouse cortical neurons expressing L213P showed the accumulation of LC3-GFP positive puncta and dystrophic neurites. Our data suggest that TrkA misfolding and aggregation induced by some CIPA mutations disrupt the autophagy homeostasis causing neurodegeneration. We propose that distinct disease-causing mutations of TrkA generate different levels of cell toxicity, which may provide an explanation of the variable intellectual disability observed in CIPA patients.

Analysis of the C9orf72 gene in patients with amyotrophic lateral sclerosis in Spain and different populations worldwide.

A hexanucleotide repeat expansion in chromosome 9 open reading frame 72 (C9orf72) can cause amyotrophic lateral sclerosis (ALS) and/or frontotemporal dementia (FTD). We assessed its frequency in 781 sporadic ALS (sALS) and 155 familial ALS (fALS) cases, and in 248 Spanish controls. We tested the presence of the reported founder haplotype among mutation carriers and in 171 Ceph Europeans from Utah (CEU), 170 Yoruba Africans, 81 Han Chinese, and 85 Japanese subjects. The C9orf72 expansion was present in 27.1% of fALS and 3.2% of sALS. Mutation carriers showed lower age at onset (P = 0.04), shorter survival (P = 0.02), greater co-occurrence of FTD (P = 8.2 × 10(-5)), and more family history of ALS (P = 1.4 × 10(-20)), than noncarriers. No association between alleles within the normal range and the risk of ALS was found (P = 0.12). All 61 of the mutation carriers were tested and a patient carrying 28 hexanucleotide repeats presented with the founder haplotype. This haplotype was found in 5.6% Yoruba Africans, 8.9% CEU, 3.9% Japanese, and 1.6% Han Chinese chromosomes.

A short in-frame deletion in NTRK1 tyrosine kinase domain caused by a novel splice site mutation in a patient with congenital insensitivity to pain with anhidrosis.

BACKGROUND: Congenital insensitivity to pain with anhidrosis (CIPA) is a rare autosomal recessive genetic disease characterized by the lack of reaction to noxious stimuli and anhidrosis. It is caused by mutations in the NTRK1 gene, which encodes the high affinity tyrosine kinase receptor I for Neurotrophic Growth Factor (NGF). CASE PRESENTATION: We present the case of a female patient diagnosed with CIPA at the age of 8 months. The patient is currently 6 years old and her psychomotor development conforms to her age (RMN, SPECT and psychological study are in the range of normality). PCR amplification of DNA, followed by direct sequencing, was used to investigate the presence of NTRK1 gene mutations. Reverse transcriptase (RT)-PCR amplification of RNA, followed by cloning and sequencing of isolated RT-PCR products was used to characterize the effect of the mutations on NTRK1 mRNA splicing. The clinical diagnosis of CIPA was confirmed by the detection of two splice-site mutations in NTRK1, revealing that the patient was a compound heterozygote at this gene. One of these alterations, c.574+1G>A, is located at the splice donor site of intron 5. We also found a second mutation, c.2206-2 A>G, not previously reported in the literature, which is located at the splice acceptor site of intron 16. Each parent was confirmed to be a carrier for one of the mutations by DNA sequencing analysis. It has been proposed that the c.574+1G>A mutation would cause exon 5 skipping during NTRK1 mRNA splicing. We could confirm this prediction and, more importantly, we provide evidence that the novel c.2206-2A>G mutation also disrupts normal NTRK1 splicing, leading to the use of an alternative splice acceptor site within exon 17. As a consequence, this mutation would result in the production of a mutant NTRK1 protein with a seven aminoacid in-frame deletion in its tyrosine kinase domain. CONCLUSIONS: We present the first description of a CIPA-associated NTRK1 mutation causing a short interstitial deletion in the tyrosine kinase domain of the receptor. The possible phenotypical implications of this mutation are discussed.