A de novo loss-of-function DYNC1H1 mutation in a patient with parkinsonian features and a favourable response to levodopa.

Graphical summary of 'A de novo loss-of-function DYNC1H1 mutation in a patient with parkinsonian features and a favourable response to levodopa' by Szczaluba et al..

Spondyloepimetaphyseal dysplasia with neurodegeneration associated with AIFM1 mutation - a novel phenotype of the mitochondrial disease.

In 1999, based on a single family, spondyloepimetaphyseal dysplasia (SEMD) with mental retardation (MR) was described as a novel syndrome with probably X-linked recessive inheritance and unknown molecular defect (MIM 300232). Our purpose was to search for the causative defect in the originally described family and in an independently ascertained second family. All patients had slowly progressive neurodegeneration with central and peripheral involvement and identical skeletal dysplasia. Whole exome sequencing performed in two subjects showed a single plausible candidate - the p.Asp237Gly variant in AIFM1 (chr. Xq26.1). The p.Asp237Gly segregated with disease as indicated by linkage analysis [maximum logarithm of odds score (LOD) score at theta 0 for the two families was 3.359]. This variant had not been previously reported and it was predicted to be pathogenic by Polyphen2, SIFT, MutationTaster and Mutation Assessor. AIFM1 encodes mitochondria associated apoptosis-inducing factor. The AIFM1 gene has been linked with COXPD6 encephalomyopathy (MIM 300816), Cowchock syndrome (MIM 310490) and X-linked deafness with neuropathy (DFNX5, MIM 300614), none of which are similar to SEMD-MR. Our results place SEMD as the third instance of a skeletal phenotype associated with a mitochondrial disease (the others being EVEN-PLUS syndrome caused by mutations of HSPA9 and CODAS syndrome due to LONP1 mutations).

KIF5A de novo mutation associated with myoclonic seizures and neonatal onset progressive leukoencephalopathy.

The KIF5A gene (OMIM 602821) encodes a neuron-specific kinesin heavy chain involved in intracellular transport of mitochondria and other cargoes. KIF5A protein comprises the N terminal motor domain, the stalk domain and the C-terminal cargo binding domain. The binding between KIF5A and its cargoes is mediated by kinesin adaptor proteins such as TRAK1 and TRAK2. Numerous missense KIF5A mutations in the motor and stalk domains cause spastic paraplegia type 10 (SPG10, OMIM 604187). Conversely, the role of loss-of-function mutations, especially those affecting the cargo binding domain, is unclear. We describe a novel de novo KIF5A p.Ser974fs/c.2921delC mutation found by whole exome sequencing in a patient with a congenital severe disease characterized by myoclonic seizures and progressive leukoencephalopathy. Since this phenotype differs considerably from the KIF5A/SPG10 disease spectrum we propose that the KIF5A p.Ser974fs and possibly other mutations which lead to truncation of the C-terminal tail of the protein cause a novel disorder. We speculate that the unique effect of the C-terminal truncating KIF5A mutations may result from the previously described complex role of this protein domain in binding of the TRAK2 and possibly other kinesin adaptor protein(s).

Next-generation sequencing for diagnosis of thoracic aortic aneurysms and dissections: diagnostic yield, novel mutations and genotype phenotype correlations.

BACKGROUND: Thoracic aortic aneurysms and dissections (TAAD) are silent but possibly lethal condition with up to 40 % of cases being hereditary. Genetic background is heterogeneous. Recently next-generation sequencing enabled efficient and cost-effective examination of gene panels. Aim of the study was to define the diagnostic yield of NGS in the 51 TAAD patients and to look for genotype-phenotype correlations within families of the patients with TAAD. METHODS: 51 unrelated TAAD patients were examined by either whole exome sequencing or TruSight One sequencing panel. We analyzed rare variants in 10 established thoracic aortic aneurysms-associated genes. Whenever possible, we looked for co-segregation in the families. Kaplan-Meier survival curve was constructed to compare the event-free survival depending on genotype. Aortic events were defined as acute aortic dissection or first planned aortic surgery. RESULTS AND DISCUSSION: In 21 TAAD patients we found 22 rare variants, 6 (27.3 %) of these were previously reported, and 16 (73.7 %) were novel. Based on segregation data, functional analysis and software estimations we assumed that three of novel variants were causative, nine likely causative. Remaining four were classified as of unknown significance (2) and likely benign (2). In all, 9 (17.6 %) of 51 probands had a positive result when considering variants classified as causative only and 18 (35.3 %) if likely causative were also included. Genotype-positive probands (n = 18) showed shorter mean event free survival (41 years, CI 35-46) than reference group, i.e. those (n = 29) without any plausible variant identified (51 years, CI 45-57, p = 0.0083). This effect was also found when the 'genotype-positive' group was restricted to probands with 'likely causative' variants (p = 0.0092) which further supports pathogenicity of these variants. The mean event free survival was particularly low (37 years, CI 27-47) among the probands with defects in the TGF beta signaling (p = 0.0033 vs. the reference group). CONCLUSIONS: This study broadens the spectrum of genetic background of thoracic aneurysms and dissections and supports its potential role as a prognostic factor in the patients with the disease.

Identification of candidate genes and mutations in QTL regions for immune responses in chicken.

There are two categories of immune responses - innate and adaptive immunity - both having polygenic backgrounds and a significant environmental component. In our study, adaptive immunity was represented by the specific antibody response toward keyhole limpet hemocyanin (KLH); innate immunity was represented by natural antibodies toward lipopolysaccharide (LPS) and lipoteichoic acid (LTA). Defining genetic bases of immune responses leads from defining quantitative trait loci (QTL) toward a single mutation responsible for variation in the phenotypic trait. The goal of the reported study was to define candidate genes and mutations for the immune traits of interest in chicken by performing an association study of SNPs located in candidate genes defined in QTL regions. Candidate genes and SNPs in QTL regions were selected in silico. SNP association was based on a custom SNP panel, GoldenGate genotyping assay (Illumina) and two statistical models: random mixed model and CAR score. The most significant SNP for immune response toward KLH was located in the JMJD6 gene located on GGA18. Four SNPs in candidate genes FOXJ1 (GGA18), EPHB1 (GGA9), PTGER4 (GGAZ) and PRKCB (GGA14) showed association with natural antibodies for LPS. A single SNP in ITGB4 (GGA18) was associated with natural antibodies for LTA. All associated SNPs mentioned above showed additive effects.

Polymorphisms of DNA repair genes and risk of squamous cell carcinoma of the head and neck in young adults.

Squamous cell carcinoma of the head and neck (HNSCC) most frequently arise in the epithelial tissues of the upper aerodigestive tract. Patients with HNSCC, aged <45 years are categorized as young adults (YA). They are characterized by more severe form of this disease and often lack of classical, causative risk factors (tobacco smoking, alcohol abusing) in comparison to older (typical) patients (OP). The study purpose was to establish an anticipated protective role of DNA repair genes polymorphisms against cancer-causing agents. It was assumed that the polymorphisms in these genes may have a significant role in the etiology of HNSCC in YA. Studies were carried out on three groups: YA group with HNSCC (n = 90), young healthy group without cancer (YH, n = 160) and OP with HNSCC (n = 205). Three polymorphisms in DNA repair genes were analyzed: XPD ex23: A35931C, XRCC1 ex10: G28152A, and XRCC3 ex7: C18067T. The choice of these genes was connected with their involvement in three different DNA repair pathways. Genotyping was carried out by polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP) technique. Statistical analysis included: calculation of odds ratio (ORs), 95 % confidence intervals (CIs) and p value. There was no significant difference in the distribution of XPD genotypes in YA compared to OP or YH. The XRCC1 AA genotype variant was observed less frequently in HNSCC YA (4.7 %) than in YH and in OP group (17.1 and 10.8 %, respectively). XRCC3 CT genotype variant was observed more frequently in HNSCC YA (61.8 %) than in YH (36.3 %) and this result is statistically significant. This variant was associated with the borderline increased risk of HNSCC development in an early age, however, a similar tendency was not observed in case of double mutated TT variant. The established differences of genotypes distribution do not seem to differentiate substantially YA and OP in head and neck cancer risk.

Polymorphisms of the DNA repair genes XRCC1 and ERCC4 are not associated with smoking- and drinking-dependent larynx cancer in a Polish population.

BACKGROUND: Tobacco smoking and alcohol drinking generate oxidative DNA damage and may contribute to larynx carcinogenesis. The X-ray repair cross complementing 1 (XRCC1) and excision repair cross-complementing rodent repair deficiency, complementation group 4 (ERCC4(XPF)) genes are important components of DNA excision repair systems, which repair DNA damage induced by various factors, including tobacco smoking and alcohol. AIM: To investigate the association between the genotypes of the XRCC1-Arg399Gln (rs25487) and ERCC4-Arg415Gln (rs1800067) polymorphisms and smoking- and drinking-related larynx cancer in a Polish population. METHODS: The polymorphisms were determined by PCR-RFLP method in 253 patients with squamous cell carcinoma of the larynx and 253 sex- and age-matched controls. RESULTS: We did not find any association between the investigated polymorphisms and larynx carcinoma, dependent on either smoking or drinking status. No association was found between these polymorphisms and larynx cancer grade, stage or age at diagnosis. CONCLUSIONS: The results indicated that Arg399Gln polymorphism of XRCC1 gene and Arg415Gln polymorphism of ERCC4 gene may not be associated with smoking- and drinking-related larynx cancer in Polish population.

Nonrandom DNA copy number changes related to lymph node metastases in squamous cell carcinoma of the lung.

Lung cancer is one of the most common malignancies and cancer-related death worldwide. Lymph node metastasis is the main cause of treatment failure. Although many studies were performed to evaluate genetic events associated with development and progression of lung cancer, molecular mechanism still remains poorly defined. In the present study, using comparative genomic hybridization (CGH) technique, we described the pattern of DNA copy number changes in a cohort of 42 primary squamous cell carcinomas (SCC) of the lung. A direct comparison of nonmetastatic (TxN0M0) and metastatic (TxN1-2M0) tumors was performed to define chromosomal imbalances related to lymph node metastases. Some genetic alterations were observed more frequently in metastatic than in non-metastatic tumors, including losses at 11q, 16p, 16q, 19p and gains at 4q, 7q, 12p, 13q, 18p. The gain at 7q with the smallest common altered region 7q31.2-q32, was found to be directly associated with lymph node involvement (p=0.0407). We suggest that the established chromosomal region harbors two putative tumor suppressor genes WNT2 and c-Met. An overexpresion of these genes seems to be involved in inducing the invasive growth and metastatic potential of SCC of the lung.

Chromosomal gains and losses indicate oncogene and tumor suppressor gene candidates in salivary gland tumors.

The incidence of salivary gland tumor in Poland is growing in the last two decades. Simultaneously a progress in understanding the genetic mechanisms of formation of this tumor was achieved by detecting several genes like PLAG1 involved in its pathogenesis. In this study we perform a whole genome, CGH analysis with the aim to identify recurrent, chromosomal copy number changes possibly indicating novel tumor suppressor gene or oncogene loci. 29 salivary tumor samples: Cystadenolymphoma-warthin (15) and adenoma polymorphum (14) located in the parotid (27) and submandibular gland (2) were collected and CGH was performed. The established copy number profiles were compared in order to asses the smallest common region of gains and losses. The delineated regions were further analyzed with the UCSC Genome Browser on Human Mar. 2006 Assembly to asses their gene content. Altogether, salivary gland tumors presented a different aberration pattern than these reported for head and neck squamous cell carcinoma (HNSCC) but no significant differences were observed between Warthin and adenoma polymorphum tumors. Moreover, several potential tumor suppressor genes and oncogenes were identified in the smallest, common altered regions. We show a frequent deletion of the harakiri gene (12q24.2) in 12/29 tumors and TP53 gene (17p13.1) in 11/29 tumors as potential tumor suppressors in salivary gland cancers. Besides, we detected a frequent amplification of the 13q22.1-22.2 region in 13/29 cases harboring the KLF5 and KLF12 genes. KLF5 regulates the expression of survivin, an oncogene widely expressed in the majority of human cancers. The observed alterations may indicate important genetic events in the formation of salivary gland tumors. Especially the amplification in 13q may be a mechanism contributing to the expression of survivin and tumor progression.

Second primary tumors (SPT) of head and neck: distinguishing of "true" SPT from micrometastasis by LOH analysis of selected chromosome regions.

The reason of treatment failures in head and neck tumors is often connected with the appearance of second primary tumors (SPT). Three mechanisms of SPT development of clonal or non clonal secondary tumors were described: 1. via micrometastases (clonal); 2. from a common carcinogenic field - Second Field Tumors (SFT - partially clonal); 3. via independent events (from different carcinogenic fields - "true" SPT - not clonal). Assessing the clonality of diagnosed tumors carries important clinical implications including chemoprevention, radiotherapy and general patient management. In this study a set of 12 microsatellite markers was used to find similarities and/or differences in allelic imbalance patterns between 22 pairs of tumors (the first tumor designate as index and SPT). The aim of the study was to identify a potential clonal origin and progression within given pairs of tumors. The results indicate that within the tumors diagnosed by clinical examination as SPT at least two mechanisms mentioned above should be taken into account as 6/23 (26%) were clonally unrelated ("true" SPT) and 3/23 (13%) carried clonal genetic changes (formation by micrometastasis or SFT). In 14/23 (61%) cases the results were insufficient or ambiguous to determine the clonality status. The final results indicate the complexity of carcinogenesis in these tumors and thus stress that clinical diagnosis of second primary tumors should be considered carefully.