Higher Mutation Burden in High Proliferation Compartments of Heterogeneous Melanoma Tumors.

Melanoma tumors are the most heterogeneous of all tumor types. Tumor heterogeneity results in difficulties in diagnosis and is a frequent cause of failure in treatment. Novel techniques enable accurate examination of the tumor cells, considering their heterogeneity. The study aimed to determine the somatic variations among high and low proliferating compartments of melanoma tumors. In this study, 12 archival formalin-fixed paraffin-embedded samples of previously untreated primary cutaneous melanoma were stained with Ki-67 antibody. High and low proliferating compartments from four melanoma tumors were dissected using laser-capture microdissection. DNA was isolated and analyzed quantitatively and qualitatively. Libraries for amplicon-based next-generation sequencing (NGS) were prepared using NEBNext Direct Cancer HotSpot Panel. NGS detected 206 variants in 42 genes in melanoma samples. Most of them were located within exons (135, 66%) and were predominantly non-synonymous single nucleotide variants (99, 73.3%). The analysis showed significant differences in mutational profiles between high and low proliferation compartments of melanoma tumors. Moreover, a significantly higher percentage of variants were detected only in high proliferation compartments (39%) compared to low proliferation regions (16%, p < 0.05). Our results suggest a significant functional role of genetic heterogeneity in melanoma.

Evidence for HNRNPH1 being another gene for Bain type syndromic mental retardation.

The HNRNPH2-associated disease (mental retardation, X-linked, syndromic, Bain type [MRXSB, MIM #300986]) is caused by de novo mutations in the X-linked HNRNPH2 gene. MRXSB has been described in six female patients with dysmorphy, developmental delay, intellectual disability, autism, hypotonia and seizures. The reported HNRNPH2 mutations were clustered in the small domain encoding nuclear localization signal; in particular, the p.Arg206Trp was found in four independent de novo events. HNRNPH1 is a conserved autosomal paralogue of HNRNPH2 with a similar function in regulation of pre-mRNAs splicing but so far it has not been associated with human disease. We describe a boy with a disease similar to MRXSB in whom a novel de novo mutation c.616C>T (p.Arg206Trp) in HNRNPH1 was found (ie, the exact paralogue of the recurrent HNRNPH2 mutation). We propose that defective function of HNRNPH2 and HNRNPH1 nuclear localization signal has similar clinical consequences. An important difference between the two diseases is that the HNRNPH1-associated syndrome may occur in boys (as in the case of our proband) which is well explained by the autosomal (chr5q35.3) rather than X-linked localization of the HNRNPH2 gene.

A novel de novo COL6A1 mutation emphasizes the role of intron 14 donor splice site defects as a cause of moderate-progressive form of ColVI myopathy - a case report and review of the genotype-phenotype correlation.

Collagen VI-related myopathy is a group of disorders affecting skeletal muscles and connective tissue. The most common symptoms are muscle weakness and joint deformities which limit the movement and progress over time. Several forms of collagen VI-related myopathies have been described: Bethlem myopathy, an intermediate form and Ullrich congenital muscular dystrophy, which is the most severe. Here we report a novel de novo c.1056+3A>C substitution in intron 14 of the COL6A1 gene encoding alpha-chains of collagen VI in a 13-year-old girl suffering from collagen VI (ColVI) myopathy. Analysis performed on cDNA generated from the RNA obtained from the patient's blood cells showed that the reported variant leads to the entire exon 14 skipping and probably results in an in-frame deletion of 18 amino acids of the COL6A1 protein. Clinical presentation, abnormal secretion of the collagen demonstrated in muscle biopsy and the COL6A1 c.1056+3A>C mutation justify classification of the presented case as ColVI myopathy with moderate-progressive course. Analysis of the literature indicates that the donor splice site of COL6A1 intron 14, associated with the phenotype of Bethlem myopathy or intermediate form, is a hot spot for ColVI myopathies.