A de novo splice site mutation in CASK causes FG syndrome-4 and congenital nystagmus.

Mutations in CASK cause X-linked intellectual disability, microcephaly with pontine and cerebellar hypoplasia, optic atrophy, nystagmus, feeding difficulties, GI hypomotility, and seizures. Here we present a patient with a de novo carboxyl-terminus splice site mutation in CASK (c.2521-2A>G) and clinical features of the rare FG syndrome-4 (FGS4). We provide further characterization of genotype-phenotype correlations in CASK mutations and the presentation of nystagmus and the FGS4 phenotype. There is considerable variability in clinical phenotype among patients with a CASK mutation, even among variants predicted to have similar functionality. Our patient presented with developmental delay, nystagmus, and severe gastrointestinal and gastroesophageal complications. From a cognitive and neuropsychological perspective, language skills and IQ are within normal range, although visual-motor, motor development, behavior, and working memory were impaired. The c.2521-2A>G splice mutation leads to skipping of exon 26 and a 9 base-pair deletion associated with a cryptic splice site, leading to a 28-AA and a 3-AA in-frame deletion, respectively (p.Ala841_Lys843del and p.Ala841_Glu868del). The predominant mutant transcripts contain an aberrant guanylate kinase domain and thus are predicted to degrade CASK's ability to interact with important neuronal and ocular development proteins, including FRMD7. Upregulation of CASK as well as dysregulation among a number of interactors is also evident by RNA-seq. This is the second CASK mutation known to us as cause of FGS4. © 2017 Wiley Periodicals, Inc.

Broadening the phenotype of LRP2 mutations: a new mutation in LRP2 causes a predominantly ocular phenotype suggestive of Stickler syndrome.

Two siblings, from a consanguineous Iraqi family, were investigated to identify the underlying genetic cause of their high myopia, esotropia, vitreous changes and cataract. Subsequent investigation identified low molecular weight proteinuria as part of their syndrome. Exome sequencing of one of the probands revealed a new non-synonymous variant in the LRP2 gene. Sanger sequencing confirmed the mutation and segregation in the family. No mutation was identified in COL9A1/2, COL11A1/2, or COL2A1 genes. The variant (c.11483A>G; p.Asp3828Gly) is predicted to be damaging and is conserved among vertebrate species. Mutations in LRP2 have been shown to cause the Donnai-Barrow syndrome (DBS) or facio-oculo-acoustico-renal (FOAR) syndrome, a syndrome associated with facial dysmorphism, ocular anomalies, sensorineural hearing loss, low molecular weight proteinuria, and diaphragmatic hernia and absent corpus callosum, although there is variability in the expression of some features. This family shows a milder phenotype with a predominant eye phenotype similar to the Stickler syndrome and only a few features of the DBS, including microglobulinuria. The presence of microglobulinuria was only detected after molecular results were known. In conclusion, with the identification of a new mutation in LRP2 associated with a predominant eye phenotype similar to the Stickler syndrome, we have broadened the phenotypic spectrum of LRP2 mutations.

Involvement of T-cell receptor-beta alterations in the development of otosclerosis linked to OTSC2.

Otosclerosis is a common form of hearing loss, characterized by disordered bone remodeling in the otic capsule. Within the otosclerotic foci, several immunocompetent cells and immune-modulating factors can be found. Different etiological theories involving the immune system have been suggested. However, a genetic component is clearly present. In large otosclerosis families, seven autosomal-dominant loci have been found, but none of the disease-causing genes has been identified. This study focused on the exploration of the second otosclerosis locus on chromosome 7q34-36 (OTSC2), holding the T-cell receptor beta locus (TRB locus). A significantly lower T-cell receptor-beta (TCR-beta) mRNA expression and percentage of blood circulating TCR-alphabeta(+) T cells was detected in OTSC2 patients compared with controls and patients with the complex form of the disease. Further analysis illustrated more significant disturbances in specific T-cell subsets, including an increased CD28(null) cell population, suggesting a disturbed T-cell development and ageing in OTSC2 patients. These disturbances could be associated with otosclerotic bone remodeling, given the known effects of immunocompetent cells on bone physiology. These data implicate the TRB locus as the causative gene in the OTSC2 region and represent an important finding in the elucidation of the disease pathology.

Detection of rare nonsynonymous variants in TGFB1 in otosclerosis patients.

Otosclerosis is one of the most common forms of hearing loss in the European population. We have identified a SNP in the TGFB1 (transforming growth factor beta 1) gene that is associated with susceptibility to otosclerosis. The protective allele of this variant, with isoleucine at position 263 of the protein, is more biologically active than the risk allele, which has a threonine in this position. Because recent studies have shown that not only common, but also rare variants can be involved in complex diseases, we performed DNA sequence analysis of the exons and intron-exon boundaries of TGFB1 in 755 otosclerosis patients and 877 control samples. We found 3 different nonsynonymous variants (E29, A29 and I241) in four otosclerosis patients, but no such changes were found in controls. In silico analysis shows that these variations could influence TGF-beta1 function and activity. Taking into account that most rare missense alleles are thought to have a biological effect, the data suggest that multiple rare amino acid changing variants in TGF-beta1 may contribute to susceptibility to otosclerosis.

Correlation between laminin-5 immunohistochemistry and human papillomavirus status in squamous cervical carcinoma.

BACKGROUND: Human papillomavirus (HPV) plays a critical role in the carcinogenesis of squamous cervical carcinoma. Integration of viral DNA into the host genome is a major contributing factor to malignant transformation. Viral load may influence integration. AIMS: To compare HPV status (type, viral load, integration status) between normal samples, carcinoma in situ and invasive carcinoma in order to elucidate the role of HPV in progression to invasive lesions. METHODS: The study population comprised 10 biopsy samples from each diagnostic group. Laminin-5 immunohistochemistry was performed to distinguish invasive carcinoma from non-invasive high-grade lesions. Real-time PCR was used to detect specific HPV types, viral load and integrated HPV, with quantification of viral E2 and E6 genes. RESULTS: Invasive carcinomas contained a higher number of laminin-5 immunoreactive cells as compared to non-invasive lesions. Almost all samples contained HPV, with a higher viral load and copy number of HPV16 integrated in E2 in cases of laminin-5 immunoreactivity and cases of invasive carcinoma. High HPV16 viral load was associated with more integrated copies in E2. CONCLUSIONS: HPV is important in progression from carcinoma in situ to invasive carcinoma. Viral load and HPV integration influence the development of cervical cancer towards invasiveness. Overall HPV status may be more predictive of patient outcome and may influence patient management.