No significant association of the 5' end of neuregulin 1 and schizophrenia in a large Danish sample

Neuregulin 1 has been implicated as a susceptibility gene in schizophrenia. Several research groups have reported association with the 5' end of the gene although no causative variant has been reported. We have investigated whether there is association with the 5' end of the gene in Danish schizophrenia patients. We found that the at-risk haplotype initially reported in the Icelandic population was not found in significant excess (or = 1.4, p = 0.12). The haplotype structure in the Danish sample was similar to that of other reported in other Caucasian populations and highly different from that of Chinese.     

A novel CLCN1 mutation (G1652A) causing a mild phenotype of thomsen disease

We investigated a 62‐year‐old man who had mild clinical features of myotonia congenita. He was found to have a novel heterozygous G‐to‐A nucleotide substitution at position 1652 in exon 15 of the CLCN1 gene. Clinicogenetic studies performed on his family revealed that his asymptomatic son also shared the mutation. We conclude that a novel chloride channel mutation (G1652A) has caused a mild form of autosomal‐dominant myotonia congenita (Thomsen disease) in this family. Muscle Nerve, 2010     

A novel presenilin 1 mutation (L174 M) in a large Cuban family with early onset Alzheimer disease

We studied a Cuban family with presenile dementia (autosomal dominant) consisting of 281 members within six generations, the proband descended from a Spanish founder. Mean age at onset was 59 years of age. Memory impairment was the main symptom in all patients, additionally, ischemic episodes were described in 4 (n=18) patients. Neuropathological examination of brain material (1 patient) revealed neuronal loss, amyloid plaques, and neurofibrillary tangles. Thirty DNA samples were genotyped (regions on chromosome 1, 3, 10, 12, 14, 17, 19, 20, and 21). A maximum Lod score of 3.79 at θ=0 was obtained for marker D14S43, located in a 9-cM interval in which all patients shared the same haplotype. Sequencing of the PSEN1 gene revealed a heterozygous base substitution, C520A (exon 6), which is predicted to cause an amino acid change from leucine to methionine in the TMIII of the presenilin 1 protein. The mutation was found to co-segregate with the disease phenotype and the associated disease haplotype. The C→A change was not observed in 80 control chromosomes from the Cuban population. Leucine at position 174 is highly conserved among species and is identical in presenilin 1 and presenilin 2 proteins. We propose the L174 M mutation might lead to an abnormal N-terminal and probably C-terminal fragments and malfunction of the protein complex. In conclusion, we found a novel PSEN1 mutation in a large family with clinical and pathological diagnosis of early onset familial Alzheimer disease, which may be relevant for other Hispanic populations. Electronic Publication     

A new truncating MPZ mutation associated with a very mild CMT1 B phenotype

We have investigated a 34-year-old female who had mild clinical and electrophysiological features of demyelinating peripheral neuropathy. She presented a novel frameshift mutation (V160fsX3) in the exon 4 of the Myelin Protein Zero (MPZ) gene. Clinical and genetic studies performed on her family revealed the same mutation in her oligosymptomatic mother and sister. Our report expands the number of MPZ mutations and indicates that mutations in exon 4 may cause a mild Charcot–Marie–Tooth type 1B phenotype.     

The C(-1019)G 5-HT1A promoter polymorphism and personality traits: no evidence for significant association in alcoholic patients

The 5HT1A receptor is one of at least 14 different receptors for serotonin which has a role in moderating several brain functions and may be involved in the aetiology of several psychiatric disorders. The C(-1019)G 5-HT1A promoter polymorphism was reported to be associated with major depression, depression-related personality traits and suicidal behavior in various samples. The G(-1019) allele carriers are prone to depressive personality traits and suicidal behavior, because serotonergic neurotransmission is reduced.     

A genetic study of Factor V Leiden (G1691A) mutation in young ischemic strokes with large vessel disease in a South Indian population

Factor V Leiden (FVL) has been, by far, the most investigated gene mutation, with 26 studies to date, on its role in arterial strokes. Overall, a meta-analysis of all these studies taken together showed that carriers of the Factor V Leiden allele were 1.33 times more likely to develop arterial strokes when compared to controls. We subjected a highly select subset of young strokes, with large vessel infarcts, to genetic analysis for FVL mutation and compared them with matched healthy controls to look for a statistically significant association. In this prospective study, 6/120 cases (5%) and 2/120 controls (1.6%) were positive for heterozygous FVL (G1691A) mutation. The higher prevalence of FVL mutation in cases (5%) compared to controls (1.6%) did not show statistical significance with a Pearson’s Chi square P value of 0.15. The Odds Ratio (OR) for risk of large vessel disease in FVL positive cases was 3.10 (95% CI of 0.61–15.7). FVL mutation (G1691A) in young Indian subjects with ischemic strokes does not seem to be significantly associated with large vessel disease.     

Two siblings with a homozygous MTHFR C677T (G80A-RFC1) mutation and stroke

Background  Stroke is a rare disorder in childhood; among its risk factors, C677T mutations in the methylenetetrahydrofolate reductase (MTHFR) gene with secondary hyperhomocysteinemia are considered. Patients and methods  We report on a family in which two brothers had arterial ischemic stroke (AIS). One of these siblings came to our observation at the age of 4 years because of decreased motility of the right arm, mild hypotrophy of the right limbs, and frequent falls: brain magnetic resonance imaging revealed a large left AIS. Family history revealed that his older brother had died at the age of 7 due to AIS. An extensive metabolic investigation revealed a homozygous C677T [G80A-reduced folate carrier 1 (RFC1)] mutation in the MTHFR gene in both the affected siblings and in their healthy older brother and heterozygous mutations in the parents. None of these family members presented hyperhomocysteinemia. Conclusions  To the best of our knowledge, this is the first family with multiple AIS patients harboring homozygous MTHFR gene C677T (G80A-RFC1) mutations without associated hyperhomocysteinemia (the latter factor is usually considered as effector of vascular damage in patients with MTHFR C677T mutations). The pathogenic hypotheses of stroke in this family are considered.     

No significant association of 14 candidate genes with schizophrenia in a large European ancestry sample: implications for psychiatric genetics

OBJECTIVE: The authors carried out a genetic association study of 14 schizophrenia candidate genes (RGS4, DISC1, DTNBP1, STX7, TAAR6, PPP3CC, NRG1, DRD2, HTR2A, DAOA, AKT1, CHRNA7, COMT, and ARVCF). This study tested the hypothesis of association of schizophrenia with common single nucleotide polymorphisms (SNPs) in these genes using the largest sample to date that has been collected with uniform clinical methods and the most comprehensive set of SNPs in each gene. METHOD: The sample included 1,870 cases (schizophrenia and schizoaffective disorder) and 2,002 screened comparison subjects (i.e. controls), all of European ancestry, with ancestral outliers excluded based on analysis of ancestry-informative markers. The authors genotyped 789 SNPs, including tags for most common SNPs in each gene, SNPs previously reported as associated, and SNPs located in functional domains of genes such as promoters, coding exons (including nonsynonymous SNPs), 3' untranslated regions, and conserved noncoding sequences. After extensive data cleaning, 648 SNPs were analyzed for association of single SNPs and of haplotypes. RESULTS: Neither experiment-wide nor gene-wide statistical significance was observed in the primary single-SNP analyses or in secondary analyses of haplotypes or of imputed genotypes for additional common HapMap SNPs. Results in SNPs previously reported as associated with schizophrenia were consistent with chance expectation, and four functional polymorphisms in COMT, DRD2, and HTR2A did not produce nominally significant evidence to support previous evidence for association. CONCLUSIONS: It is unlikely that common SNPs in these genes account for a substantial proportion of the genetic risk for schizophrenia, although small effects cannot be ruled out.     

Cancer risk in association with Parkinson disease: A population-based study

PurposeData from large population-based studies on the association between Parkinson disease (PD) and the risk of developing cancer are scarce. We compared the risk of developing incident cancer between patients with or without PD.MethodsWe conducted a population-based follow-up study and a nested case-control analysis using data from the UK-based General Practice Research Database. We included PD patients aged ≥40 years with a first PD diagnosis between 1994 and 2005, and a matched comparison group free of PD. We assessed cancer incidence rates and relative risk estimates (odds ratios [ORs] with 95% confidence intervals [CI]).ResultsThe risk of developing cancer overall was lower in PD patients as compared to patients without PD (crude incidence rate ratio 0.77, 95% CI 0.64–0.92). In the nested case-control analysis (adj. OR for all cancers 0.72, 95% CI 0.59–0.87) the risk reduction was strongest for smoking-related cancers (adj. OR 0.47, 95% CI 0.31–0.72). The adjusted OR for hematological malignancies was 0.32 (95% CI 0.14–0.74). Due to small numbers, ORs for other cancer entities did not reach statistical significance.ConclusionsWith the exception of melanoma, PD patients were less likely to develop cancer than individuals without PD in this large observational study.     

LRRK2 G2019S mutation and Parkinson's disease: a clinical, neuropsychological and neuropsychiatric study in a large Italian sample

We analysed the Leucine-Rich Repeat Kinase 2 (LRRK2) gene for the G2019S mutation in 1245 consecutive, unrelated patients with primary degenerative parkinsonism, and collected information on medical history, motor, cognitive and neuropsychiatric functions to characterize the clinical phenotype associated to the G2019S mutation. The mutation was detected in heterozygous state in 19 probands (1.7%), and in five additional affected relatives. Clinical features in carriers were those of typical, idiopathic Parkinson's disease. However, behavioural abnormalities were frequent (87%), suggesting a more widespread limbic involvement in G2019S carriers.     

Analysis of the PINK1 gene in a large cohort of cases with Parkinson disease

BACKGROUND: Mutations in the PTEN-induced kinase (PINK1) gene located within the PARK6 locus on chromosome 1p35-p36 have recently been identified in patients with recessive early-onset Parkinson disease. OBJECTIVE: To assess the prevalence of PINK1 mutations within a series of early- and late-onset Parkinson disease patients living in North America. DESIGN: All coding exons of the PINK1 gene were sequenced in a series of 289 Parkinson disease patients and 80 neurologically normal control subjects; the mutation frequencies were evaluated in additional controls (100 white and 50 Filipino subjects). RESULTS: We identified 27 variants, including the first reported compound heterozygous mutation (Glu240Lys and Leu489Pro) and a homozygous Leu347Pro mutation in 2 unrelated young-onset Parkinson disease patients. CONCLUSION: Autosomal recessive mutations in PINK1 are a rare cause of young-onset Parkinson disease.     

De novo truncating mutation in SCN1A as a cause of febrile seizures plus (FS+)

SCN1A is one of the most relevant epilepsy genes. In general, de novo severe mutations, such as truncating mutations, lead to a classic form of Dravet syndrome (DS), while missense mutations are associated with both DS and milder phenotypes within the GEFS+ spectrum, however, these phenotype‐genotype correlations are not entirely consistent. Case report. We report an 18‐year‐old woman with a history of recurrent febrile generalized tonic‐clonic seizures (GTCS) starting at age four months and afebrile asymmetric GTCS and episodes of arrest, suggestive of focal impaired awareness seizures, starting at nine months. Her psychomotor development was normal. Sequencing of SCN1A revealed a heterozygous de novo truncating mutation (c.5734C>T, p.Arg1912X) in exon 26. Conclusion. Truncating mutations in SCN1A may be associated with milder phenotypes within the GEFS+ spectrum. Accordingly, SCN1A gene testing should be performed as part of the assessment for sporadic patients with mild phenotypes that fit within the GEFS+ spectrum, since the finding of a mutation has diagnostic, therapeutic and genetic counselling implications.     

The association of beta-site APP cleaving enzyme (BACE) C786G polymorphism with Alzheimer's disease

The deposition of amyloid beta-peptide (Abeta) plays a crucial role in the pathogenesis of Alzheimer's disease (AD). Beta-site APP cleaving enzyme (BACE) is the rate-limiting enzyme in the Abeta formation. BACE mutations/polymorphisms may be associated with AD. We searched the BACE coding region mutations/polymorphisms of cDNA in 25 AD patients and 100 healthy controls by single-strand conformational polymorphism. A polymorphism at BACE coding region was identified and confirmed to be 786C/G polymorphism by nucleotide sequencing. Based on these findings, we investigated the association of this polymorphism with the occurrence of AD by PCR-RFLP. A total of 98 AD patients along with 138 controls were recruited in the present study. The allele frequencies of the 786C/G polymorphism were 0.622 for C and 0.378 for G in AD. In controls, the C and G allele frequencies were 0.691 and 0.309, respectively. No significant association of this polymorphism with the occurrence of AD can be established. Larger sample size may be necessary to identify other potential mutations/polymorphisms among BACE gene.     

A novel mutation (G114V) in the prion protein gene in a family with inherited prion disease

Inherited prion diseases are characterized by mutations in the PRNP gene encoding the prion protein (PrP). We report a novel missense mutation in the PRNP gene (resulting in a G114V mutation in PrP) in members of a Uruguayan family with clinical and histopathologic features of prion disease. Affected individuals were characterized by an early age at onset, initial neuropsychiatric symptoms, late dementia with prominent pyramidal and extrapyramidal symptoms, and long disease duration.     

Parkinson syndrome, neuropathy, and myopathy caused by the mutation A8344G (MERRF) in tRNALys

We describe a patient who presented with parkinsonism associated with the A8344G myoclonus epilepsy, ataxia, and myopathy with ragged red fibers mutation in the tRNA(Lys) gene. In addition, neurogenic changes and mitochondrial myopathy with ragged red fibers were observed. Neither myoclonus epilepsy nor other clinical signs described in association with A8344G were noted. Similar to previously reported patients with parkinsonism and mtDNA deletions, the symptoms of our patient responded favorably to levodopa therapy.