KRAS Mutational Regression Is Associated With Oligo-Metastatic Status and Good Prognosis in Metastatic Colorectal Cancer.

BACKGROUND: We previously reported that loss of KRAS mutations ("regressive" mutational trajectories) from primary tumors to metastases associated with the oligo-metastatic status in colorectal cancer (CRC). The present study was undertaken in order to analyze the mutational trajectories of KRAS in a well-characterized cohort of CRC patients who developed poly- or oligo-metastatic disease. MATERIAL AND METHODS: Patients were treated and followed-up according to European Society of Medical Oncology guidelines. Primary CRC FFPE tissue and metastatic circulating-free DNA were extracted using the QIAamp DNA specific kits (Qiagen, Hilden, Germany). Samples were sequenced with the Oncomine Solid Tumour DNA kit (Thermo Fisher Scientific, Waltham, MA, USA). Plasma collection for liquid biopsy was done from 1 to 14 days before starting first-line chemotherapy. Analysis of the prognostic power of KRAS evolutionary trajectories was done with uni- and multivariate analyses. RESULTS: One-hundred-fourteen patients were enrolled. Sixty-three patients presented with mutated KRAS (mutKRAS) and 51 with wild-type KRAS (wtKRAS). KRAS mutational concordance was high (70.1%).Two divergent subsets were identified: mutKRAS in primary tumors and wtKRAS in metastatic ones (regressive: mutKRAS → wtKRAS in 8.8% of patients), and vice versa (progressive: wtKRAS → mutKRAS in 21.1% of patients). An association between KRAS regressive trajectory and the oligo-metastatic status (P <0.0001) was found. At multivariate analysis, regressive and progressive mutational trajectories emerged as independent prognostic factors for survival, with Hazard Ratios of 0.22 (CI 95%: 0.08-0.61; median survival: not reached) and 2.70 (CI 95%: 1.11-6.56, median survival: 12.1 months), respectively. CONCLUSIONS: Our data provide evidence that the evolutionary trajectories of KRAS can have a strong clinical prognostic role and that they can be involved in discriminating between poly-metastatic aggressive vs oligo-metastatic indolent CRC.

Mutations in the PCYT1A gene are responsible for isolated forms of retinal dystrophy.

Mutations in the PCYT1A gene have been recently linked to two different phenotypes: one characterized by spondylometaphyseal dysplasia and cone-rod dystrophy (SMD-CRD) and the other by congenital lipodystrophy, severe fatty liver disease, and reduced HDL cholesterol without any retinal or skeletal involvement. Here, we identified, by next generation sequencing, sequence variants affecting function in the PCYT1A gene in three young patients with isolated retinal dystrophy from two different Italian families. A thorough clinical evaluation of the patients, with whole skeleton X-ray, metabolic assessment and liver ultrasound failed to reveal signs of skeletal dysplasia, metabolic and hepatic alterations. This is the first report showing that the PCYT1A gene can be responsible for isolated forms of retinal dystrophy, particularly without any skeletal involvement, thus further expanding the phenotypic spectrum induced by mutations in this gene.

[Next Generation Sequencing and ADPKD].

Autosomal Dominant Polycistic Kidney Disease (ADPKD) is the most common inherited genetic disorder in the word, caused by mutations in PKD1 gene in 85% of cases and PKD 2 gene in the remaining 15%. Although diagnosis is usually based on ultrasound, MRI and CT scans, in some cases genetic testing is necessary, for example, in patients with atypical phenotype or with a negative family history, or in cases of donation from relatives. The presence of pseudogenes in PKD1, the size of the gene, the costs of the Sanger sequencing and genetic heterogeneity underlying kidney disease make genetic analysis particularly difficult to be performed. Next Generation Sequencing (NGS) represents the last frontier of innovation among diagnostic tools for molecular diagnosis of inherited cystic kidney disease thanks to the ability to analyze several genes at the same time. In this regard, we have developed a NGS platform, called Nephroplex, with the aim of identifying variations in 115 genes responsible for numerous kidney diseases, including cystic and polycystic disease, achieving, overall, a target region of 338.8 kbps. The technology used for the enrichment is HaloPlex system, based on the digestion of genomic DNA with restriction enzymes and the capture of the regions of interest with specific hybridization probes. With our platform, we have analyzed 9 patients with clinical diagnosis of ADPKD. We have obtained a depth coverage of 100x for 96.5% of the target, while the region not covered accounted for only 3% of the region of interest. In 6 patients, we found causative mutations in the genes PKD1 and PKD2, achieving a detection rate of 66%. In conclusion, the NephroPlex platform has proved to be an excellent device for molecular diagnosis of kidney disease and could clarify the mechanisms underlying genetic heterogeneity observed in kidney disease.

Familial exudative vitreoretinopathy caused by a homozygous mutation in TSPAN12 in a cystic fibrosis infant.

Familial exudative vitreoretinopathy (FEVR) is a genetic disease affecting the vascularization of the peripheral retina. The clinical manifestations are very heterogeneous, ranging from mildly affected patients, who could present no visual defects, to severe conditions which can also cause complete blindness at birth or in the first decade. FEVR can be inherited in all the three genetic forms: dominant, recessive and X-linked. To date, four genes have been associated with the condition: TSPAN12. NDP. FDZ4 and LRP5. Interestingly, mutations in TSPAN12 have been considered causative of both a dominant and recessive inheritance and a FEVR phenotype sensitive to the number of TSPAN12 mutations has been supposed. Here we describe a case of a female infant affected by cystic fibrosis and by a severe form of exudative vitreoretinopathy. In particular, we have detected the homozygous missense mutation c.668 T > C in TSPAN12. Neither of the heterozygous parents has ocular manifestations of the disease, suggesting a classic recessive mendelian pattern of inheritance.