A NOVEL DISEASE-CAUSING NF1 VARIANT IN A CROATIAN FAMILY WITH NEUROFIBROMATOSIS TYPE 1

Neurofibromatosis type 1 (NF1) is the most common autosomal dominant neurocutaneous syndrome with the estimated prevalence ranging from 1 in 3000 to 1 in 4000 individuals and wide phenotypical variability. NF1 is caused by autosomal dominant heterozygous mutations in the neurofibromin gene which is located on the chromosome 17 (17q11.2). Phenotypically, NF1 patients have a very heterogeneous clinical phenotype. In this study, a novel frameshift NF1 variant was identified in a Croatian family with NF1 (mother and two daughters). The novel variant c. 4482_4483delTA leads to sequence change that creates a premature translational stop signal (p.His1494Glnfs*7) in the NF1 gene. Our study showed that even when the same germline NF1 variant has been identified, there is still huge phenotypic variability in patients even within the same family, and it makes prognosis of the disease more complex. The development of next-generation sequencing technologies which allow rapid and accurate identification of disease-causing mutations becomes crucial for molecular characterization of NF1 patients as well as for patient follow-up, in the context of genetic counseling and clinical management of patients

A NOVEL DISEASE-CAUSING NF1 VARIANT IN A CROATIAN FAMILY WITH NEUROFIBROMATOSIS TYPE 1

Neurofibromatosis type 1 (NF1) is the most common autosomal dominant neurocutaneous syndrome with the estimated prevalence ranging from 1 in 3000 to 1 in 4000 individuals and wide phenotypical variability. NF1 is caused by autosomal dominant heterozygous mutations in the neurofibromin gene which is located on the chromosome 17 (17q11.2). Phenotypically, NF1 patients have a very heterogeneous clinical phenotype. In this study, a novel frameshift NF1 variant was identified in a Croatian family with NF1 (mother and two daughters). The novel variant c. 4482_4483delTA leads to sequence change that creates a premature translational stop signal (p.His1494Glnfs*7) in the NF1 gene. Our study showed that even when the same germline NF1 variant has been identified, there is still huge phenotypic variability in patients even within the same family, and it makes prognosis of the disease more complex. The development of next-generation sequencing technologies which allow rapid and accurate identification of disease-causing mutations becomes crucial for molecular characterization of NF1 patients as well as for patient follow-up, in the context of genetic counseling and clinical management of patients

Complex intrachromosomal rearrangement in 1q leading to 1q32.2 microdeletion: a potential role of SRGAP2 in the gyrification of cerebral cortex

BACKGROUND: Van der Woude syndrome (MIM: 119300, VWS) is a dominantly inherited and the most common orofacial clefting syndrome; it accounts for ~2 % of all cleft lip and palate cases. Intellectual disability (ID) is characterized by significant limitations, both in intellectual functioning (cognitive deficit) and in adaptive behavior as expressed in conceptual, social and practical adaptive skills. Karyotyping has been the first standard test for the detection of genetic imbalance in patients with ID for more than 35 years. Advances in genetic diagnosis have laid chromosomal microarrays (CMA) as a new standard and first first-line test for diagnosis of patients with ID, as well as other conditions, such as autism spectrum disorders or multiple congenital anomalies. ----- CASE PRESENTATION: The present case was initially studied due to unexplained cognitive deficit. Physical examination at the age of 18 years revealed cleft palate, lower lip pits and hypodontia, accompanied with other dysmorphic features and absence of speech. Brain MRI uncovered significantly reduced overall volume of gray matter and cortical gyrification. Banding cytogenetics revealed an indistinct intrachromosomal rearrangement in the long arm of one chromosome 1, and subsequent microarray analyses identified a 5.56 Mb deletion in 1q32.1-1q32.3, encompassing 52 genes; included were the entire IRF6 gene (whose mutations/deletions underlay VWS) and SRGAP2, a gene with an important role in neuronal migration during development of cerebral cortex. Besides, a duplication in 3q26.32 (1.9 Mb in size) comprising TBL1XR1 gene was identified. Multicolor banding for chromosome 1 and molecular cytogenetics applying a battery of locus-specific probes covering 1q32.1 to 1q44 characterized a four breakpoint-insertional-rearrangement-event, resulting in 1q32.1-1q32.3 deletion. ----- CONCLUSIONS: Considering that the human-specific three-fold segmental duplication of SRGAP2 gene evolutionary corresponds to the beginning of neocortical expansion, we hypothesize that aberrations in SRGAP2 are strong candidates underlying specific brain abnormalities, namely reduced volume of grey matter and reduced gyrification

Aberrant expression of shared master-key genes contributes to the immunopathogenesis in patients with juvenile spondyloarthritis

Association of juvenile spondyloarthritis (jSpA) with the HLA-B27 genotype is well established, but there is little knowledge of other genetic factors with a role in the development of the disease. To date, only a few studies have tried to find those associated genes by obtaining expression profiles, but with inconsistent results due to various patient selection criteria and methodology. The aim of the present study was to identify and confirm gene signatures and novel biomarkers in highly homogeneous cohorts of untreated and treated patients diagnosed with jSpA and other forms of juvenile idiopathic arthritis (JIA) according to ILAR criteria. For the purposes of the research, total RNA was isolated from whole blood of 45 children with jSpA and known HLA genotype, 11 children with oligo- and polyarticular forms of JIA, as well as 12 age and sex matched control participants without diagnosis of inflammatory disease. DNA microarray gene expression was performed in 11 patients with jSpA and in four healthy controls, along with bioinformatical analysis of retrieved data. Carefully selected differentially expressed genes where analyzed by qRT-PCR in all participants of the study. Microarray results and bioinformatical analysis revealed 745 differentially expressed genes involved in various inflammatory processes, while qRT-PCR analysis of selected genes confirmed data universality and specificity of expression profiles in jSpA patients. The present study indicates that jSpA could be a polygenic disease with a possible malfunction in antigen recognition and activation of immunological response, migration of inflammatory cells and regulation of the immune system. Among genes involved in these processes TLR4, NLRP3, CXCR4 and PTPN12 showed almost consistent expression in study patients diagnosed with jSpA. Those genes and their products could therefore potentially be used as novel biomarkers, possibly predictive of disease prognosis and response to therapy, or even as a target for new therapeutic approaches

Clinical and pathohistological characteristics of Alport spectrum disorder caused by COL4A4 mutation c.193-2A>C: a case series

Aim To present the pathohistological and clinical charac - teristics of five Croatian families with Alport spectrum dis - orders caused by splice acceptor pathogenic variant c.193- 2A>C in COL4A4 at the genomic position chr2:227985866. Methods The study enrolled five probands with kidney bi - opsy analysis and five family members. Mutation screening was performed with Illumina MiSeq platform. The patho - genic variant was confirmed with standard dye-terminator sequencing. Results The only homozygous patient, aged two, had pro - teinuria and hematuria with preserved kidney function and no extrarenal manifestations. This patient had chang - es characteristic for Alport syndrome observed on elec - tron microscopy of the kidney biopsy. In the heterozygous group, six patients had hematuria, four biopsied probands had proteinuria, and only one had moderately reduced kidney function. Heterozygous probands had variable kid - ney biopsy findings. Three patients had thin glomerular basement membrane nephropathy visible on electron mi - croscopy and focal segmental glomerulosclerosis on light microscopy, two of them with focal lamellation on elec - tron microscopy. One heterozygous patient had changes characteristic for Alport syndrome on electron microscopy without focal segmental glomerulosclerosis. Conclusion The homozygous patient had hematuria and proteinuria with preserved kidney function. The heterozy - gous patients presented with reasonably mild clinical phe - notype and variable pathohistological findings

The prevalence and genotype of 21-hydroxylase deficiency in the Croatian Romani population

ObjectiveCongenital adrenal hyperplasia (CAH) owing to 21-hydroxylase deficiency (21-OHD) is a rare autosomal recessive disorder caused by pathological variants in the CYP21A2 gene. After a high prevalence of classic 21-OHD CAH in the Romani population was reported in the Republic of North Macedonia, we decided to estimate the prevalence of 21-OHD in Croatia and, if high, assess the possible causes and estimate the frequency of particular CYP21A2 variants.DesignCross-sectional study.MethodsData from a Croatian 21-OHD genetic database was reviewed, and only Romani patients were included in the study. CYP21A2 genotyping was performed using allele-specific PCR, MLPA, and Sanger sequencing.ResultsAccording to a survey conducted in 2017, Croatia had 22,500 Romani people and six of them had a salt-wasting (SW) form of 21-OHD. All were homozygous for the c.IVS2-13A/C-G pathological variant in intron 2 and descended from consanguineous families belonging to different Romani tribes. The calculated prevalence of 21-OHD in Croatian Romani is 1:3,750, while in the Croatian general population, it is 1:18,000. Three of the six Romani patients originated from two neighboring villages in North-western Croatia (Slavonia County), as well as the seventh patient who is of mixed Romani/Croatian descent and heterozygous for the c.IVS2-13A/C-G pathological variant (not included in the prevalence calculation).ConclusionA high prevalence of SW 21-OHD in the Croatian Romani population caused by the homozygous cIVS2-13A/C-G pathological variant was found. In addition to isolation and consanguinity, other possible reasons could be the heterozygous advantage of the CYP21A2 gene pathological variant and the bottleneck effect as a result of the Romani Holocaust in World War II

Convergence of miRNA Expression Profiling, α-Synuclein Interacton and GWAS in Parkinson's Disease

miRNAs were recently implicated in the pathogenesis of numerous diseases, including neurological disorders such as Parkinson's disease (PD). miRNAs are abundant in the nervous system, essential for efficient brain function and play important roles in neuronal patterning and cell specification. To further investigate their involvement in the etiology of PD, we conducted miRNA expression profiling in peripheral blood mononuclear cells (PBMCs) of 19 patients and 13 controls using microarrays. We found 18 miRNAs differentially expressed, and pathway analysis of 662 predicted target genes of 11 of these miRNAs revealed an over-representation in pathways previously linked to PD as well as novel pathways. To narrow down the genes for further investigations, we undertook a parallel approach using chromatin immunoprecipitation-sequencing (ChIP-seq) analysis to uncover genome-wide interactions of α-synuclein, a molecule with a central role in both monogenic and idiopathic PD. Convergence of ChIP-seq and miRNomics data highlighted the glycosphingolipid biosynthesis and the ubiquitin proteasome system as key players in PD. We then tested the association of target genes belonging to these pathways with PD risk, and identified nine SNPs in USP37 consistently associated with PD susceptibility in three genome-wide association studies (GWAS) datasets (0.46≤OR≤0.63) and highly significant in the meta-dataset (3.36×10−4<p<1.94×10−3). A SNP in ST8SIA4 was also highly associated with PD (p = 6.15×10−3) in the meta-dataset. These findings suggest that several miRNAs may act as regulators of both known and novel biological processes leading to idiopathic PD