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Bi-allelic mutations in FBXO7 are classically associated with a complex phenotype, known as parkinsonian-pyramidal syndrome. We describe two brothers affected by typical early onset Parkinson's disease (EOPD), who carry novel compound heterozygous variants in FBXO7. Our report highlights that typical EOPD can be part of an expanding FBXO7-related phenotype.

Recessive mutations in PRKN, PARK7, and PINK1 are established causes of early-onset Parkinson's disease (EOPD). Previous studies have interrogated the role of heterozygous variants in these genes but mainly focused on rare (minor allele frequency [MAF]lt;1%) damaging variants or established mutations. Here, we assessed heterozygous private PRKN, PARK7 and PINK1 variants in PD risk in four large-scale PD case-control datasets by performing gene-wise burden analyses using sequencing data totaling 5,829 PD cases and 7,221 controls, and summary allele counts from 9,501 PD cases and 48,207 controls. Results showed no significant burden in all three genes after meta-analyses. Burden in EOPD (age at onsetlt;50 years) and late-onset PD (≥50 years) remained nonsignificant. In summary, we found no evidence to support the association of the excess burden of heterozygous private variants in PRKN, PARK7, and PINK1 with PD risk in the European population. Larger, more diverse cohorts are needed to accurately determine their role in PD.

ATP5F1B is a subunit of the mitochondrial ATP synthase or complex V of the mitochondrial respiratory chain. Pathogenic variants in nuclear genes encoding assembly factors or structural subunits are associated with complex V deficiency, typically characterized by autosomal recessive inheritance and multisystem phenotypes. Movement disorders have been described in a subset of cases carrying autosomal dominant variants in structural subunits genes ATP5F1A and ATP5MC3. Here, we report the identification of two different ATP5F1B missense variants (c.1000A>C; p.Thr334Pro and c.1445T>C; p.Val482Ala) segregating with early-onset isolated dystonia in two families, both with autosomal dominant mode of inheritance and incomplete penetrance. Functional studies in mutant fibroblasts revealed no decrease of ATP5F1B protein amount but severe reduction of complex V activity and impaired mitochondrial membrane potential, suggesting a dominant-negative effect. In conclusion, our study describes a new candidate gene associated with isolated dystonia and confirms that heterozygous variants in genes encoding subunits of the mitochondrial ATP synthase may cause autosomal dominant isolated dystonia with incomplete penetrance, likely through a dominant-negative mechanism.

Lysosomes are highly dynamic organelles implicated in multiple diseases. Using live super-resolution microscopy, we found that lysosomal tethering events rarely undergo lysosomal fusion, but rather untether over time to reorganize the lysosomal network. Inter-lysosomal untethering events are driven by a mitochondrial Mid51/Fis1 complex that undergoes coupled oligomerization on the outer mitochondrial membrane. Importantly, Fis1 oligomerization mediates TBC1D15 (Rab7-GAP) mitochondrial recruitment to drive inter-lysosomal untethering via Rab7 GTP hydrolysis. Moreover, inhibiting Fis1 oligomerization by either mutant Fis1 or a Mid51 oligomerization mutant potentially associated with Parkinson’s disease prevents lysosomal untethering events, resulting in misregulated lysosomal network dynamics. In contrast, dominant optic atrophy–linked mutant Mid51, which does not inhibit Mid51/Fis1 coupled oligomerization, does not disrupt downstream lysosomal dynamics. As Fis1 conversely also regulates Mid51 oligomerization, our work further highlights an oligomeric Mid51/Fis1 mitochondrial complex that mechanistically couples together both Drp1 and Rab7 GTP hydrolysis machinery at mitochondria–lysosome contact sites. These findings have significant implications for organelle networks in cellular homeostasis and human disease.

Objective: The study was undertaken to identify a monogenic cause of early onset, generalized dystonia. Methods: Methods consisted of genome-wide linkage analysis, exome and Sanger sequencing, clinical neurological examination, brain magnetic resonance imaging, and protein expression studies in skin fibroblasts from patients. Results: We identified a heterozygous variant, c.388G>A, p.Gly130Arg, in the eukaryotic translation initiation factor 2 alpha kinase 2 (EIF2AK2) gene, segregating with early onset isolated generalized dystonia in 5 patients of a Taiwanese family. EIF2AK2 sequencing in 191 unrelated patients with unexplained dystonia yielded 2 unrelated Caucasian patients with an identical heterozygous c.388G>A, p.Gly130Arg variant, occurring de novo in one case, another patient carrying a different heterozygous variant, c.413G>C, p.Gly138Ala, and one last patient, born from consanguineous parents, carrying a third, homozygous variant c.95A>C, p.Asn32Thr. These 3 missense variants are absent from gnomAD, and are located in functional domains of the encoded protein. In 3 patients, additional neurological manifestations were present, including intellectual disability and spasticity. EIF2AK2 encodes a kinase (protein kinase R [PKR]) that phosphorylates eukaryotic translation initiation factor 2 alpha (eIF2α), which orchestrates the cellular stress response. Our expression studies showed abnormally enhanced activation of the cellular stress response, monitored by PKR-mediated phosphorylation of eIF2α, in fibroblasts from patients with EIF2AK2 variants. Intriguingly, PKR can also be regulated by PRKRA (protein interferon-inducible double-stranded RNA-dependent protein kinase activator A), the product of another gene causing monogenic dystonia. Interpretation: We identified EIF2AK2 variants implicated in early onset generalized dystonia, which can be dominantly or recessively inherited, or occur de novo. Our findings provide direct evidence for a key role of a dysfunctional eIF2α pathway in the pathogenesis of dystonia. ANN NEUROL 2021;89:485–497.

Objectives The majority of people with suspected genetic dystonia remain undiagnosed after maximal investigation, implying that a number of causative genes have not yet been recognised. We aimed to investigate this paucity of diagnoses. Methods We undertook weighted burden analysis of whole‐exome sequencing data from 138 individuals with unresolved generalised dystonia of suspected genetic aetiology, followed by additional case‐finding from international databases, first for the gene implicated by the burden analysis (VPS16), then for other functionally related genes. Electron microscopy was performed on patient‐derived cells. Results Analysis revealed a significant burden for VPS16 (Fisher's exact test p‐value, 6.9x10−9). VPS16 encodes a subunit of the homotypic fusion and vacuole protein sorting (HOPS) complex, which plays a key role in autophagosome‐lysosome fusion. A total of 18 individuals harbouring heterozygous loss‐of‐function VPS16 variants, and one with a microdeletion, were identified. These individuals experienced early‐onset progressive dystonia with predominant cervical, bulbar, orofacial and upper limb involvement. Some patients had a more complex phenotype with additional neuropsychiatric and/or developmental comorbidities. We also identified biallelic loss‐of‐function variants in VPS41, another HOPS‐complex encoding genes, in an individual with infantile‐onset generalised dystonia. Electron microscopy of patient‐derived lymphocytes and fibroblasts from both VPS16 and VPS41 patients showed vacuolar abnormalities suggestive of impaired lysosomal function. Interpretation Our study strongly supports a role for HOPS complex dysfunction in the pathogenesis of dystonia, though variants in different subunits display different phenotypic and inheritance characteristics.

Parkinson’s disease (PD) is a complex neurodegenerative disorder with a strong genetic component, where most known disease-associated variants are single nucleotide polymorphisms (SNPs) and small insertions and deletions (Indels). DNA repetitive elements account for >50% of the human genome, however little is known of their contribution to PD etiology. While select short tandem repeats (STRs) within candidate genes have been studied in PD, their genome-wide contribution remains unknown. Here we present the first genome-wide association study (GWAS) of STRs in PD. Through a meta-analysis of 16 imputed GWAS cohorts from the International Parkinson’s Disease Genomic Consortium (IPDGC), totalling 39,087 individuals (16,642 PD cases and 22,445 controls of European ancestry) we identified 34 genome-wide significant STR loci (p < 5.34×10-6), with the strongest signal located inKANSL1(chr17:44205351:[T]11, p=3×10-39, OR=1.31 [CI 95%=1.26-1.36]). Conditional-joint analyses suggested that 4 significant STRs mapping nearbyNDUFAF2, TRIML2, MIRNA-129-1andNCOR1were independent from known PD risk SNPs. Including STRs in heritability estimates increased the variance explained by SNPs alone. Gene expression analysis of STRs (eSTR) in RNASeq data from 13 brain regions, identified significant associations of STRs influencing the expression of multiple genes, including PD known genes. Further functional annotation of candidate STRs revealed that significant eSTRs withinNUDFAF2andZSWIM7overlap with regulatory features and are associated with change in the expression levels of nearby genes. Here we show that STRs at known and novel candidate PD loci contribute to PD risk, and have functional effects in disease-relevant tissues and pathways, supporting previously reported disease-associated genes and giving further evidence for their functional prioritization. These data represent a valuable resource for researchers currently dissecting PD risk loci.

BACKGROUND Childhood-onset dystonia is often genetically determined. Recently, KMT2B variants have been recognized as an important cause of childhood-onset dystonia. OBJECTIVE To define the frequency of KMT2B mutations in a cohort of dystonic patients aged

The Mediator multiprotein complex functions as a regulator of RNA polymerase II-catalyzed gene transcription. In this study, exome sequencing (ES) detected biallelic putative disease-causing variants in MED27, encoding Mediator Complex Subunit 27, in sixteen patients from eleven families with a novel neurodevelopmental syndrome. Patient phenotypes are highly homogeneous including global developmental delay, intellectual disability, axial hypotonia with distal spasticity, dystonic movements, and cerebellar hypoplasia. Seizures and cataracts were noted in severely affected individuals. Identification of multiple patients with biallelic MED27 variants supports the critical role of MED27 in normal human neural development, particularly for the cerebellum. This article is protected by copyright. All rights reserved.

Mutations in KCNQ2, which encodes a pore-forming K+ channel subunit responsible for neuronal M-current, cause neonatal epileptic encephalopathy, a complex disorder presenting with severe early-onset seizures and impaired neurodevelopment. The condition is exceptionally difficult to treat, partially because the effects of KCNQ2 mutations on the development and function of human neurons are unknown. Here, we used induced pluripotent stem cells (iPSCs) and gene editing to establish a disease model and measured the functional properties of differentiated excitatory neurons. We find that patient iPSC-derived neurons exhibit faster action potential repolarization, larger post-burst afterhyperpolarization and a functional enhancement of Ca2+-activated K+ channels. These properties, which can be recapitulated by chronic inhibition of M-current in control neurons, facilitate a burst-suppression firing pattern that is reminiscent of the interictal electroencephalography pattern in patients. Our findings suggest that dyshomeostatic mechanisms compound KCNQ2 loss-of-function leading to alterations in the neurodevelopmental trajectory of patient iPSC-derived neurons.

BACKGROUND Monogenic causes of isolated dystonia are heterogeneous. Assembling cohorts of affected individuals sufficiently large to establish new gene-disease relationships can be challenging. OBJECTIVE We sought to expand the catalogue of monogenic etiologies for isolated dystonia. METHODS After the discovery of a candidate variant in a multicenter exome-sequenced cohort of affected individuals with dystonia, we queried online platforms and genomic data repositories worldwide to identify subjects with matching genotypic profiles. RESULTS Seven different biallelic loss-of-function variants in AOPEP were detected in five probands from four unrelated families with strongly overlapping phenotypes. In one proband, we observed a homozygous nonsense variant (c.1477C>T [p.Arg493*]). A second proband harbored compound heterozygous nonsense variants (c.763C>T [p.Arg255*]; c.777G>A [p.Trp259*]), whereas a third proband possessed a frameshift variant (c.696_697delAG [p.Ala234Serfs*5]) in trans with a splice-disrupting alteration (c.2041-1G>A). Two probands (siblings) from a fourth family shared compound heterozygous frameshift alleles (c.1215delT [p.Val406Cysfs*14]; c.1744delA [p.Met582Cysfs*6]). All variants were rare and expected to result in truncated proteins devoid of functionally important amino acid sequence. AOPEP, widely expressed in developing and adult human brain, encodes a zinc-dependent aminopeptidase, a member of a class of proteolytic enzymes implicated in synaptogenesis and neural maintenance. The probands presented with disabling progressive dystonia predominantly affecting upper and lower extremities, with variable involvement of craniocervical muscles. Dystonia was unaccompanied by any additional symptoms in three families, whereas the fourth family presented co-occurring late-onset parkinsonism. CONCLUSIONS Our findings suggest a likely causative role of predicted inactivating biallelic AOPEP variants in cases of autosomal recessive dystonia. Additional studies are warranted to understand the pathophysiology associated with loss-of-function variation in AOPEP. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Biallelic Parkin (PRKN) mutations cause autosomal recessive Parkinson’s disease (PD); however, the role of monoallelic PRKN mutations as a risk factor for PD remains unclear. We investigated the role of single heterozygous PRKN mutations in three large independent case-control cohorts totalling 10 858 PD cases and 8328 controls. Overall, after exclusion of biallelic carriers, single PRKN mutations were more common in PD than controls conferring a >1.5-fold increase in the risk of PD [P-value (P) = 0.035], with meta-analysis (19 574 PD cases and 468 488 controls) confirming increased risk [Odds ratio (OR) = 1.65, P = 3.69E-07]. Carriers were shown to have significantly younger ages at the onset compared with non-carriers (NeuroX: 56.4 vs. 61.4 years; exome: 38.5 vs. 43.1 years). Stratifying by mutation type, we provide preliminary evidence for a more pathogenic risk profile for single PRKN copy number variant (CNV) carriers compared with single nucleotide variant carriers. Studies that did not assess biallelic PRKN mutations or consist of predominantly early-onset cases may be biasing these estimates, and removal of these resulted in a loss of association (OR = 1.23, P = 0.614; n = 4). Importantly, when we looked for additional CNVs in 30% of PD cases with apparent monoallellic PRKN mutations, we found that 44% had biallelic mutations, suggesting that previous estimates may be influenced by cryptic biallelic mutation status. While this study supports the association of single PRKN mutations with PD, it highlights confounding effects; therefore, caution is needed when interpreting current risk estimates. Together, we demonstrate that comprehensive assessment of biallelic mutation status is essential when elucidating PD risk associated with monoallelic PRKN mutations.

Early-onset Parkinson’s disease (EOPD) can be caused by biallelic mutations in PRKN, DJ1 and PINK1. However, while the identification of novel genes is becoming increasingly challenging, new insights into EOPD genetics have important relevance for understanding the pathways driving disease pathogenesis. Here, using extended runs of homozygosity (ROH) >8Mb as a marker for possible autosomal recessive inheritance, we identified 90 EOPD patients with extended ROH. Investigating rare, damaging homozygous variants to identify candidate genes for EOPD, 81 genes were prioritised. Through the assessment of biallelic (homozygous and compound heterozygous) variant frequencies in cases and controls from three independent cohorts totalling 3,381 PD patients and 2,463 controls, we identified two biallelic MIEF1 variant carriers among EOPD patients. We further investigated the role of disease-associated variants in MIEF1 which encodes for MID51, an outer mitochondrial membrane protein, and found that putative EOPD-associated variants in MID51 preferentially disrupted its oligomerization state. These findings provide further support for the role of mitochondrial dysfunction in the development of PD. Together, we have used genome-wide homozygosity mapping to identify potential EOPD genes, and future studies incorporating expanded datasets and further functional analyses will help to determine their roles in disease aetiology.

The NUS1 gene was recently associated with Parkinson’s disease (PD) in the Chinese population. Here, as part of the International Parkinson’s Disease Genomics Consortium (IPDGC), we have leveraged large-scale PD case-control cohorts to comprehensively assess the NUS1 association in individuals of European descent. Burden analysis of rare nonsynonymous damaging variants across case-control individuals from whole-exome and -genome datasets did not find evidence of NUS1 association with PD. Overall, single variant tests for rare (MAF0.01) variants, including 15 PD-GWAS cohorts and summary statistics from the largest PD GWAS meta-analysis to date, also did not uncover any associations. Our results indicate a lack of evidence for a role of rare damaging nonsynonymous NUS1 variants in PD in unrelated case-control cohorts of European descent, suggesting that the previously observed association could be driven by extremely rare population-specific variants.

Biallelic PARK2 (Parkin) mutations cause autosomal recessive Parkinson’s (PD); however, the role of monoallelic PARK2 mutations as a risk factor for PD remains unclear. We investigated the role of single heterozygous PARK2 mutations in three large independent case-control cohorts totalling 10,858 PD cases and 8,328 controls. Overall, after exclusion of biallelic carriers, single PARK2 mutations were more common in PD than controls conferring a >1.5-fold increase in risk of PD (P=0.035), with meta-analysis (19,574 PD cases and 468,488 controls) confirming increased risk (OR=1.65, P=3.69E-07). Carriers were shown to have significantly younger ages at onset compared to non-carriers (NeuroX: 56.4 vs. 61.4 years; Exome: 38.5 vs. 43.1 years). Stratifying by mutation type, we provide preliminary evidence for a more pathogenic risk profile for single PARK2 copy number variant (CNV) carriers compared to single nucleotide variant carriers. Studies that did not assess biallelic PARK2 mutations or consist of predominantly early-onset cases may be biasing these estimates, and removal of these resulted in a loss of association (OR=1.23, P=0.614; n=4). Importantly, when we looked for additional CNVs in 30% of PD cases with apparent monoallellic PARK2 mutations we found that 44% had biallelic mutations suggesting that previous estimates may be influenced by cryptic biallelic mutation status. While this study supports the association of single PARK2 mutations with PD, it highlights confounding effects therefore caution is needed when interpreting current risk estimates. Together, we demonstrate that comprehensive assessment of biallelic mutation status is essential when elucidating PD risk associated with monoallelic PARK2 mutations.

Parkinson’s disease (PD) is a complex neurodegenerative disorder with a strong genetic component. We performed a “hypothesis-free” exome-wide burden-based analysis of different variant frequencies, predicted functional impact and age of onset classes, in order to expand the understanding of rare variants in PD. Analyzing whole-exome data from a total of 1,425 PD cases and 596 controls, we found a significantly increased burden of ultra-rare (URV= private variants absent from gnomAD) protein altering variants (PAV) in early-onset PD cases (EOPD, −26, beta=0.16, SE=0.02), compared to LOPD cases (>60 years old, late-onset), where more common PAVs (allele frequencies

The NUS1 gene was recently associated with Parkinson’s disease (PD) in the Chinese population. Here, as part of the International Parkinson’s Disease Genomics Consortium, we have leveraged large-scale PD case-control cohorts to comprehensively assess damaging NUS1 variants in individuals of European descent. Burden analysis of rare nonsynonymous damaging variants across case-control individuals from whole-exome and -genome data sets did not find evidence of NUS1 association with PD. Overall, single-variant tests for rare (minor allele frequency0.01) variants, including 15 PD-GWAS cohorts and summary statistics from the largest PD GWAS meta-analysis to date, also did not uncover any associations. Our results indicate a lack of evidence for a role of rare damaging nonsynonymous NUS1 variants in PD in unrelated case-control cohorts of European descent, suggesting that the previously observed association could be driven by extremely rare population-specific variants.

VPS13 protein family members VPS13A through VPS13C have been associated with various recessive movement disorders. We describe the first disease association of rare recessive VPS13D variants including frameshift, missense, and partial duplication mutations with a novel complex, hyperkinetic neurological disorder. The clinical features include developmental delay, a childhood onset movement disorder (chorea, dystonia, or tremor), and progressive spastic ataxia or paraparesis. Characteristic brain magnetic resonance imaging shows basal ganglia or diffuse white matter T2 hyperintensities as seen in Leigh syndrome and choreoacanthocytosis. Muscle biopsy in 1 case showed mitochondrial aggregates and lipidosis, suggesting mitochondrial dysfunction. These findings underline the importance of the VPS13 complex in neurological diseases and a possible role in mitochondrial function. Ann Neurol 2018;83:1089-1095.

BACKGROUND: Recent genomewide association study meta-analyses have identified 28 loci associated with risk of Parkinson's disease (PD). We sought to investigate whether these genetic risk factors are associated with PD age at onset. METHODS: Genetic risk scores from these loci were calculated for 6,249 cases. Linear regression tested associations between cumulative genetic risk and PD age at onset. RESULTS: Increasing genetic risk scores were associated with earlier age at onset (beta = -0.10, P = 2.92 × 10(-8) , adjusted r(2) = 0.27). Single standard deviation increase in genetic risk score is associated with 37.44 d earlier age at onset. Highest genetic risk was found at 31 to 60 y, onset slightly below average age at onset (AAO). CONCLUSIONS: Common genetic risk factors have a small but consistent association with AAO in PD.

Mutations in the TANK-binding kinase 1 (TBK1) gene have recently been shown to cause frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). The phenotype is highly variable and has been associated with behavioral variant FTD, primary progressive aphasia, and pure ALS. We describe the clinical, anatomical, and pathological features of a patient who developed corticobasal syndrome (CBS)/progressive nonfluent aphasia (PNFA) overlap. The patient presented with progressive speech difficulties and later developed an asymmetric akinetic–rigid syndrome. Neuroimaging showed asymmetrical frontal atrophy, predominantly affecting the right side. There was a strong family history of neurodegenerative disease with four out of seven siblings developing either dementia or ALS in their 50s and 60s. The patient died at the age of 71 and the brain was donated for postmortem analysis. Histopathological examination showed frontotemporal lobar degeneration TDP-43 type A pathology. Genetic screening did not reveal a mutation in the GRN, MAPT, or C9orf72 genes, but exome sequencing revealed a novel p.E703X mutation in the TBK1 gene. Although segregation data were not available, this loss-of-function mutation is highly likely to be pathogenic because it is predicted to disrupt TBK1/optineurin interaction and impair cellular autophagy. In conclusion, we show that TBK1 mutations can be a cause of an atypical parkinsonian syndrome and screening should be considered in CBS patients with a family history of dementia or ALS.

Background Attention-deficit/hyperactivity disorder (ADHD) is characterized by deficits in reward sensitivity and response inhibition. The relative contribution of these frontostriatal mechanisms to ADHD symptoms and their genetic determinants is largely unexplored. Methods Using functional magnetic resonance imaging and genetic analysis of the monoamine oxidase A ( MAOA ) gene, we investigated how striatal and inferior frontal activation patterns contribute to ADHD symptoms depending on MAOA genotype in a sample of adolescent boys ( n = 190). Results We demonstrate an association of ADHD symptoms with distinct blood oxygen level–dependent (BOLD) responses depending on MAOA genotype. In A hemizygotes of the expression single nucleotide polymorphism rs12843268, which express lower levels of MAOA , ADHD symptoms are associated with lower ventral striatal BOLD response during the monetary incentive delay task and lower inferior frontal gyrus BOLD response during the stop signal task. In G hemizygotes, ADHD symptoms are associated with increased inferior frontal gyrus BOLD response during the stop signal task in the presence of increased ventral striatal BOLD response during the monetary incentive delay task. Conclusions Depending on MAOA genotype, ADHD symptoms in adolescent boys are associated with either reward deficiency or insufficient response inhibition. Apart from its mechanistic interest, our finding may aid in developing pharmacogenetic markers for ADHD.

The last 5 years have seen rapid progress in Parkinson’s disease (PD) genetics, with the publication of a series of large-scale genome wide association studies for PD, and evaluation of the roles of the LRRK2 and GBA genes in the aetiology of PD. We are beginning to develop a coherent picture of the interplay of Mendelian and non-Mendelian factors in PD. Pathways involved in mitochondrial quality control (mitophagy), lysosomal function and immune function are emerging as important in the pathogenesis of PD. These pathways represent a target for therapeutic intervention and a way in which the heterogeneity of disease cause, as well as disease mechanism, can be established. In the future, there is likely to be an individualised basis for the treatment of PD, linked to the identification of specific genetic factors.

Previously we have localized to chromosome 3q21-q24, a predisposition locus for colorectal cancer (CRC), through a genome-wide linkage screen (GWLS) of 69 families without familial adenomatous polyposis or hereditary non-polyposis CRC. To further investigate Mendelian susceptibility to CRC, we extended our screen to include a further GWLS of an additional 34 CRC families. We also searched for a disease gene at 3q21-q24 by linkage disequilibrium mapping in 620 familial CRC cases and 960 controls by genotyping 1676 tagging SNPs and sequencing 30 candidate genes from the region. Linkage analysis was conducted using the Affymetrix 10K SNP array. Data from both GWLSs were pooled and multipoint linkage statistics computed. The maximum NPL score (3.01; P=0.0013) across all families was at 3q22, maximal evidence for linkage coming from families segregating rectal CRC. The same genomic position also yielded the highest multipoint heterogeneity LOD (HLOD) score under a dominant model (HLOD=2.79; P=0.00034), with an estimated 43% of families linked. In the case-control analysis, the strongest association was obtained at rs698675 (P=0.0029), but this was not significant after adjusting for multiple testing. Analysis of candidate gene mapping to the region of maximal linkage on 3q22 failed to identify a causal mutation. There was no evidence for linkage to the previously reported 9q CRC locus (NPL=0.95, P=0.23; HLOD(dominant)=0.40, HLOD(recessive)=0.20). Our findings are consistent with the hypothesis that variation at 3q22 contributes to the risk of CRC, but this is unlikely to be mediated through a restricted set of alleles.

OBJECTIVE: Colorectal cancer (CRC) has a substantial heritable component. Common genetic variation has been shown to contribute to CRC risk. A study was conducted in a large multi-population study to assess the feasibility of CRC risk prediction using common genetic variant data combined with other risk factors. A risk prediction model was built and applied to the Scottish population using available data. DESIGN: Nine populations of European descent were studied to develop and validate CRC risk prediction models. Binary logistic regression was used to assess the combined effect of age, gender, family history (FH) and genotypes at 10 susceptibility loci that individually only modestly influence CRC risk. Risk models were generated from case-control data incorporating genotypes alone (n=39,266) and in combination with gender, age and FH (n=11,324). Model discriminatory performance was assessed using 10-fold internal cross-validation and externally using 4187 independent samples. The 10-year absolute risk was estimated by modelling genotype and FH with age- and gender-specific population risks. RESULTS: The median number of risk alleles was greater in cases than controls (10 vs 9, p5% predicted 10-year absolute risk. CONCLUSION: Genotype data provide additional information that complements age, gender and FH as risk factors, but individualised genetic risk prediction is not currently feasible. Nonetheless, the modelling exercise suggests public health potential since it is possible to stratify the population into CRC risk categories, thereby informing targeted prevention and surveillance.

Recent genome-wide association studies have identified single-nucleotide polymorphisms at 16 genetic loci associated with colorectal cancer risk: rs6691170 (1q41), rs10936599 (3q26.2), rs16892766 (8q23.3), rs6983267 (8q24.21), rs10795668 (10p14), rs3802842 (11q23.1), rs11169552 (12q13.13), rs4444235, rs1957636 (14q22.2), rs4779584 (15q13.3), rs9929218 (16q22.1), rs4939827 (18q21.1), rs10411210 (19q13.11), rs961253 and rs4813802 (20p12.3) and rs4925386 (20q13.33). In the present study, we examined whether these variants are preferentially associated with tumour subtype-tumour site, stage, degree of differentiation and microsatellite instability status-in 3146 patients. Several loci showed statistically significant associations with specific phenotypes notably rs6691170 and rs3802842 associated with microsatellite stable rectal disease; rs4779584, rs961253 and rs4813802 associated with microsatellite stable colonic disease and rs4444235 and rs4925386 with microsatellite instability colonic disease. These findings are consistent with pathogenic variants in loci differentially impacting on distinct morphogenetic pathways consistent with aetiologically different risk factors in the development of colorectal cancer.

The -93G > A (rs1800734) polymorphism within the core promoter region of the MutL homolog 1 (MLH1) gene has recently been proposed as a low penetrance variant for colorectal cancer (CRC). We evaluated the significance of rs1800734 on CRC risk by genotyping 10 409 CRC cases and 6965 controls. The per allele odds ratio (OR) for all CRC-associated MLH1-93G > A was 1.06 (P = 0.037). Using a subset of 3132 cases with known microsatellite instability (MSI) status, the risk was shown to be confined to microsatellite instability-high (MSI-H) CRC; OR = 1.39 (P = 1.45 × 10(-4)). A meta-analysis of our study and four smaller published studies (totalling 801 cases, 10 890 controls) provided for increased evidence of relationship between MLH1-93G > A and MSI-H CRC risk (P = 3.43 × 10(-12)). The impact of MLH1-93G > A on CRC risk was shown to be independent of the 14 low penetrance loci for CRC identified by recent genome-wide association studies. These data provide further evidence that MLH1-93G > A is a low-penetrance variant for CRC and support the proposition that MLH1-93G > A acts as marker for a somatic event defining a specific CRC subtype.

Transforming growth factor-â (TGF-â) signalling plays a key role in colorectal cancer (CRC). Bone morphogenetic protein-4 (BMP4) is a member of the TGF-â family of signal transduction molecules. To examine if germline mutation in BMP4 causes CRC we analysed 504 genetically enriched CRC cases (by virtue of early-onset disease, family history of CRC) for mutations in the coding sequence of BMP4. We identified three pathogenic mutations, p.R286X (g.8330C>T), p.W325C (g.8449G>T) and p.C373S (g.8592G>C), amongst the CRC cases which were not observed in 524 healthy controls. p.R286X localizes to the N-terminal of the TGF-â1 prodomain truncating the protein prior to the active domain. p.W325C and p.C373S mutations are predicted from protein homology modelling with BMP2 to impact deleteriously on BMP4 function. Segregation of p.C373S with adenoma and hyperplastic polyp in first-degree relatives of the case suggests germline mutations may confer a juvenile polyposis-type phenotype. These findings suggest mutation of BMP4is a cause of CRC and the value of protein-based modelling in the elucidation of rare disease-causing variants. © 2010 Wiley-Liss, Inc.

Background Parkinson’s disease (PD) is a common neurodegenerative disorder, for which genetics plays a small yet significant component of its complex aetiology. Copy number variants (CNVs), involving duplications or deletions of DNA segments of varying length, are increasingly recognised to contribute to PD pathogenesis and risk. Aims The present study investigated CNV prevalence in 191 PD patients from across the country (175 autosomal dominant, 3 autosomal recessive, 13 sporadic). Additionally, 10 PD patients with previously identified PARK2 mutations were analysed for second mutations which would indicate compound heterozygous states. Methods Multiplex ligation-dependent probe amplification (MLPA) was used to identify CNVs in known PD genes, using SALSA P051 and P052 probe kits (MRC Holland), which contained probes for all exons of SNCA, PARK2, UCLH1, PINK1, DJ-1, LRRK2 and ATP13A2. Raw data was analysed using GeneMapper Software, with deletion/duplication boundaries delineated by ≤0.75 and≥1.25 ratio values respectively. Results A total of 11 exon duplications/deletions in the PD genes PARK2, SNCA, DJ-1 and PINK1 were identified, indicating that 5% of our PD cohort possessed CNVs. Significant findings include 3 whole gene SNCA duplications, a heterozygous PARK2 exon 2 deletion in a pseudo-dominant PD patient, a novel heterozygous DJ-1 duplication of exons 2,3,5,6,7 and a novel homozygous PINK1 deletion of exon 1. Conclusions Whilst further clinical and genetic information requires incorporation with our findings, the present study emphasises the importance of CNV detection in PD, and contributes to current work exploring the role of single heterozygous PARK2 CNVs in PD risk.

Background Parkinson’s disease (PD) is associated with motor and non-motor symptoms, including cognitive impairment. Genetic features may influence clinical symptoms. Objective Familial PD patients have been recruited through the ABN British Neurological Surveillance Unit (BNSU) to the Parkinson’s Families Project. A primary aim of this study is to examine how genetic factors influence phenotype. We present baseline clinical data and a description of cognitive impairment in familial PD patients from this cohort. Methods Eligible patients are referred through the BNSU. Blood samples are collected for DNA. Systematic clinical data is collected using a similar approach to the Tracking Parkinson’s (PRoBaND) study. Results 101 patients with familial PD have been recruited to date from participating hospitals or remotely. Cognitive outcomes were assessed in the Montreal Cognitive Assessment (MoCA). In the first 85 familial PD patients, 27.1% of patients met criteria for mild cognitive impairment, 10.6% patients met criteria for severe cognitive impairment, and 62.4% of patients had normal cognition. Analysis of genetic data is underway and results with rare Mendelian mutations will be reported. Conclusions The BNSU is an essential source of recruitment to the Parkinson’s Families Project. Identification of genetic factors that influence phenotype will lead to new drug targets.

Part of the inherited susceptibility to colorectal cancer (CRC) is caused by the coinheritance of common low risk variants. E-cadherin (CDH1) has an established role in CRC; somatic inactivation of CDH1 is a common early event, and germline mutations can cause early-onset CRC. The -160C>A promoter variant (rs16260) of CDH1 has been reported to influence CDH1 transcription and thereby represents a strong candidate for a predisposition locus. To examine this proposition, we conducted a two-staged association study based on genotyping a total of 5,679 CRC cases and 5,412 controls for rs16260. CDH1-160C>A genotype was associated with CRC risk (P-trent=0.001). Compared to common homozygotes, the odds ratios (ORs) of CRC associated with heterozygous and homozygote variant genotype were 0.90 (95% confidence interval [CI]: 0.84-0.97) and 0.81 (95% CI: 0.71-0.93), respectively. In combination with the previously identified 8q21, 8q24, 10p14, 11q 15q13.3 and 18q21 risk variants, the risk of CRC increases with an increasing numbers of variant alleles for the 7 loci, ORper (allele)=1.16; 95% CI: 1.13-1.19; P-trend=1.68 x 10(-34)). These data indicate CDH1-160C>A is a risk factor for CRC, and because a high proportion of the European population are carriers of at-risk genotypes, the variant is likely to contribute substantially to the development of CRC. Furthermore, our study underscores the importance of conducting association studies using large sample series to demonstrate polymorphic variants conferring modest relative risks. (C) 2009 UICC

Background Pseudoxanthoma elasticum (PXE) is an autosomal recessive metabolic disorder with ectopic mineralization in the skin, eyes and cardiovascular system. PXE is caused by mutations in ABCC6 . Objective To examine 54 unrelated South African PXE patients for ABCC6 PXE causing mutations. Methods Patients were screened for mutations in ABCC6 using two strategies. The first involved a comprehensive screening of all the ABCC6 exons and flanking regions by dHPLC or sequencing whereas the second involved screening patients only for the common PXE mutations. The ABCC6 gene was screened in ten white and ten black healthy unrelated South Africans in order to examine the level of common non-PXE associated variation. Results The Afrikaner founder mutation, R1339C, was present in 0.41 of white ABCC6 PXE alleles, confirming the founder effect and its presence in both Afrikaans- (34/63 PXE alleles) and English-speakers (4/28). Eleven mutations were detected in the white patients (of European origin), including two nonsense mutations, 6 missense mutations, two frameshift mutations and a large deletion mutation. The five "Coloured" patients (of mixed Khoisan, Malay, European and African origin) included three compound heterozygotes with R1339C as one of the mutations. The three black patients (sub-Saharan African origin) were all apparent homozygotes for the R1314W mutation. Blacks showed a trend towards a higher degree of neurtral variation (18 variants) when compared to whites (12 variants). Conclusion Delineation of the ABCC6 mutation profile in South African PXE patients will be used as a guide for molecular genetic testing in a clinical setting and for genetic counselling.

Several lines of evidence implicate mitochondrial dysfunction in the development of cancer. To test the hypothesis that common mtDNA variation influences the risk of colorectal cancer (CRC), we genotyped 132 tagging mtDNA variants in a sample of 2854 CRC cases and 2822 controls. The variants examined capture approximately 80% of mtDNA common variation (excluding the hypervariable D-loop). We first tested for single marker associations; the strongest association detected was with A5657G (P=0.06). Overall the distribution of association P-values was consistent with a null distribution. Next, we classified individuals into the nine common European haplogroups and compared their distribution in cases and controls. This analysis also provided no evidence of an association between mitochondrial variation and CRC risk. In conclusion, our results provide little evidence that mitochondrial genetic background plays a role in modifying an individual's risk of developing CRC.

The common single-nucleotide polymorphism (SNP) rs3802842 at 11q23.1 has recently been reported to be associated with risk of colorectal cancer (CRC). To examine this association in detail we genotyped rs3802842 in eight independent case-control series comprising a total of 10 638 cases and 10 457 healthy individuals. A significant association between the C allele of rs3802842 and CRC risk was found (per allele OR = 1.17; 95% confidence interval [CI]: 1.12-1.22; P = 1.08 x 10(-12)) with the risk allele more frequent in rectal than colonic disease (P = 0.02). In combination with 8q21, 8q24, 10p14, 11q, 15q13.3 and 18q21 variants, the risk of CRC increases with an increasing numbers of variant alleles for the six loci (OR(per allele) = 1.19; 95% CI: 1.15-1.23; P(trend) = 7.4 x 10(-24)). Using the data from our genome-wide association study of CRC, LD mapping and imputation, we were able to refine the location of the causal locus to a 60 kb region and screened for coding changes. The absence of exonic mutations in any of the transcripts (FLJ45803, LOC120376, C11orf53 and POU2AF1) mapping to this region makes the association likely to be a consequence of non-coding effects on gene expression.

Resume Objectif Evaluer les associations entre les polymorphismes genetiques du cluster de genes de l’interleukine-1 (IL-1) et la susceptibilite et la severite de la polyarthrite rhumatoide (PR) chez les noirs d’Afrique du Sud. Methodes Les frequences alleliques et genotypiques d’ IL1B (−511) et (+3954) et le nombre de variable de repetitions en tandem (VNTR) d’ IL1RN (VNTR) et (+2018) ont ete comparees chez 141 patients atteints de PR et 101 sujets sains. Resultats Nous n’avons pas mis en evidence de differences significatives dans la distribution allelique des quatre loci entre les patients atteints de PR et les temoins. Dans le groupe PR, l’ IL1RN *2 (deux repetions d’une sequence de 86 pb) sur le locus IL1RN VNTR etait associe de facon independante a des scores radiologiques de Larsen (LDS), corriges en fonction de la duree de la maladie ( p = 0,04). De plus, l’haplotype concerne, IL1RN *2 et l’allele C’ (+2018), etaient associes a un LDS plus eleve de 15 points en moyenne, compare a l’haplotype de base de l’allele IL1RN * long (trois repetitions ou plus) et l’allele T (+2018) ( p = 0,009). L’allele T classique IL-1B (−511) etait associe au score HAQ discretement modifie ( p = 0,02). Conclusion Nos resultats renforcent l’idee d’un role possible des polymorphismes du cluster de gene de l’IL-1 dans la severite de la PR, et en particulier IL1RN *2 comme marqueur d’erosion osseuse chez les noirs d’Afrique du Sud atteints de PR.

To identify colorectal cancer (CRC) susceptibility alleles, we conducted a genome-wide association study. In phase 1, we genotyped 550,163 tagSNPs in 940 familial colorectal tumor cases (627 CRC, 313 high-risk adenoma) and 965 controls. In phase 2, we genotyped 42,708 selected SNPs in 2,873 CRC cases and 2,871 controls. In phase 3, we evaluated 11 SNPs showing association at P < 10(-4) in a joint analysis of phases 1 and 2 in 4,287 CRC cases and 3,743 controls. Two SNPs were taken forward to phase 4 genotyping (10,731 CRC cases and 10,961 controls from eight centers). In addition to the previously reported 8q24, 15q13 and 18q21 CRC risk loci, we identified two previously unreported associations: rs10795668, located at 10p14 (P = 2.5 x 10(-13) overall; P = 6.9 x 10(-12) replication), and rs16892766, at 8q23.3 (P = 3.3 x 10(-18) overall; P = 9.6 x 10(-17) replication), which tags a plausible causative gene, EIF3H. These data provide further evidence for the 'common-disease common-variant' model of CRC predisposition.

Alcohol abuse is highly prevalent, but little is understood about the molecular causes. Here, we report that Ras suppressor 1 (Rsu1) affects ethanol consumption in flies and humans. Drosophila lacking Rsu1 show reduced sensitivity to ethanol-induced sedation. We show that Rsu1 is required in the adult nervous system for normal sensitivity and that it acts downstream of the integrin cell adhesion molecule and upstream of the Ras-related C3 botulinum toxin substrate 1 (Rac1) GTPase to regulate the actin cytoskeleton. In an ethanol preference assay, global loss of Rsu1 causes high naive preference. In contrast, flies lacking Rsu1 only in the mushroom bodies of the brain show normal naive preference but then fail to acquire ethanol preference like normal flies. Rsu1 is, thus, required in distinct neurons to modulate naive and acquired ethanol preference. In humans, we find that polymorphisms in RSU1 are associated with brain activation in the ventral striatum during reward anticipation in adolescents and alcohol consumption in both adolescents and adults. Together, these data suggest a conserved role for integrin/Rsu1/Rac1/actin signaling in modulating reward-related phenotypes, including ethanol consumption, across phyla.

EIF4G1 mutations were previously reported as a cause of Parkinson's disease (PD). As a result of this finding, considerable work has been performed to test this idea and to examine the functional role of eukaryotic translation initiation factor 4-gamma in the pathogenic process underlying PD. Here, we show that the originally described mutation is likely a rare benign variant. We tested this variant in a very large series of subjects and show that it is more frequent in controls than cases. We argue here that this infers that EIF4G1 mutations are not related to PD.

GTP cyclohydrolase 1, encoded by the GCH1 gene, is an essential enzyme for dopamine production in nigrostriatal cells. Loss-of-function mutations in GCH1 result in severe reduction of dopamine synthesis in nigrostriatal cells and are the most common cause of DOPA-responsive dystonia, a rare disease that classically presents in childhood with generalized dystonia and a dramatic long-lasting response to levodopa. We describe clinical, genetic and nigrostriatal dopaminergic imaging ([(123)I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) tropane single photon computed tomography) findings of four unrelated pedigrees with DOPA-responsive dystonia in which pathogenic GCH1 variants were identified in family members with adult-onset parkinsonism. Dopamine transporter imaging was abnormal in all parkinsonian patients, indicating Parkinson's disease-like nigrostriatal dopaminergic denervation. We subsequently explored the possibility that pathogenic GCH1 variants could contribute to the risk of developing Parkinson's disease, even in the absence of a family history for DOPA-responsive dystonia. The frequency of GCH1 variants was evaluated in whole-exome sequencing data of 1318 cases with Parkinson's disease and 5935 control subjects. Combining cases and controls, we identified a total of 11 different heterozygous GCH1 variants, all at low frequency. This list includes four pathogenic variants previously associated with DOPA-responsive dystonia (Q110X, V204I, K224R and M230I) and seven of undetermined clinical relevance (Q110E, T112A, A120S, D134G, I154V, R198Q and G217V). The frequency of GCH1 variants was significantly higher (Fisher's exact test P-value 0.0001) in cases (10/1318 = 0.75%) than in controls (6/5935 = 0.1%; odds ratio 7.5; 95% confidence interval 2.4-25.3). Our results show that rare GCH1 variants are associated with an increased risk for Parkinson's disease. These findings expand the clinical and biological relevance of GTP cycloydrolase 1 deficiency, suggesting that it not only leads to biochemical striatal dopamine depletion and DOPA-responsive dystonia, but also predisposes to nigrostriatal cell loss. Further insight into GCH1-associated pathogenetic mechanisms will shed light on the role of dopamine metabolism in nigral degeneration and Parkinson's disease.

The Parkinson9s Families Project is a multi-centre genetic epidemiology study. Aims To identify new genetic variants that predispose to or cause familial or early onset PD. Methods Families with either familial or early onset PD are recruited. The ABN BNSU is a source of participant recruitment, by which patients with familial PD from across the UK can be notified to the study team monthly by ABN members. Permission to contact the patient is obtained from the patient through the consultant. Following informed consent, patients provide blood samples for genetic analysis and complete standard study questionnaires. Results (April 2015–Jan 2016): Over 10 months we have received 96 BNSU referrals (mean 10/month) from 33 consultants. We have received 35 permission-to-contact forms from patients (36.5%) and 19 patients/families have completed study enrollment (19.8% recruitment rate). Conclusions The BNSU is an invaluable source of referral for patients with rare diseases from across the UK, and we currently have a 20% patient recruitment rate. However, there is a delay from study initiation to completion of patient recruitment. We could improve the relatively low rate of patient contact by establishing a formal system of regular follow-ups for consultants and an anonymised tracking system for BNSU-referred patients. Finally, we suggest the possibility of multi-source recruitment through Parkinson9s UK, local study sites, geriatricians and PD nurses.

To identify risk variants for colorectal cancer (CRC), we conducted a genome-wide association study, genotyping 550,163 tag SNPs in 940 individuals with familial colorectal tumor (627 CRC, 313 advanced adenomas) and 965 controls. We evaluated selected SNPs in three replication sample sets (7,473 cases, 5,984 controls) and identified three SNPs in SMAD7 (involved in TGF-beta and Wnt signaling) associated with CRC. Across the four sample sets, the association between rs4939827 and CRC was highly statistically significant (P(trend) = 1.0 x 10(-12)).

Common genetic variation at human 14q22.2 tagged by rs4444235 is significantly associated with colorectal cancer (CRC) risk. Re-sequencing was used to comprehensively annotate the 17kb region of strong linkage disequilibrium encompassing rs4444235. Through bioinformatic analyses using H3K4Me1, H3K4Me3, and DNase-I hypersensitivity chromatin signatures and evolutionary conservation we identified seven candidate disease-causing single-nucleotide polymorphisms mapping to six regions within the 17-kb region predicted to have regulatory potential. Reporter gene studies of these regions demonstrated that the element to which rs4444235 maps acts as an allele-specific transcriptional enhancer. Allele-specific expression studies in CRC cell lines heterozygous for rs4444235 showed significantly increased expression of bone morphogenetic protein-4 (BMP4) associated with the risk allele (P, We acknowledge the National Health Service (NHS) funding to the National Institute for Health Research (NIHR) Biomedical Research Centre. Finally, we are grateful to all patients and individuals for participation. Cancer Research UK (C1298/A8362 supported by the Bobby Moore Fund) provided principal funding for the study. JLG-S acknowledges grants from the Spanish Ministry of Education and Science (BFU2010-14839 and CSD2007-00008) and Junta de Andalucía (CVI-3488). SJL is in receipt of a PhD studentship from Cancer Research UK. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/207-2013) under grant no. 258236, FP7 collaborative project SYSCOL.

BACKGROUND: Defective DNA repair has a causal role in hereditary colorectal cancer (CRC). Defects in the base excision repair gene MUTYH are responsible for MUTYH-associated polyposis and CRC predisposition as an autosomal recessive trait. Numerous reports have suggested MUTYH mono-allelic variants to be low penetrance risk alleles. We report a large collaborative meta-analysis to assess and refine CRC risk estimates associated with bi-allelic and mono-allelic MUTYH variants and investigate age and sex influence on risk.METHODS: MUTYH genotype data were included from 20 565 cases and 15 524 controls. Three logistic regression models were tested: a crude model; adjusted for age and sex; adjusted for age, sex and study.RESULTS: All three models produced very similar results. MUTYH bi-allelic carriers demonstrated a 28-fold increase in risk (95% confidence interval (CI): 6.95-115). Significant bi-allelic effects were also observed for G396D and Y179C/G396D compound heterozygotes and a marginal mono-allelic effect for variant Y179C (odds ratio (OR) = 1.34; 95% CI: 1.00-1.80). A pooled meta-analysis of all published and unpublished datasets submitted showed bi-allelic effects for MUTYH, G396D and Y179C (OR = 10.8, 95% CI: 5.02-23.2; OR = 6.47, 95% CI: 2.33-18.0; OR = 3.35, 95% CI: 1.14-9.89) and marginal mono-allelic effect for variants MUTYH (OR = 1.16, 95% CI: 1.00-1.34) and Y179C alone (OR = 1.34, 95% CI: 1.01-1.77).CONCLUSIONS: Overall, this large study refines estimates of disease risk associated with mono-allelic and bi-allelic MUTYH carriers. British Journal of Cancer (2010) 103, 1875-1884. doi:10.1038/sj.bjc.6605966 www.bjcancer.com Published online 9 November 2010 (C) 2010 Cancer Research UK

Mutations in protein kinases can drive cancer through alterations of the kinase activity or by uncoupling kinase activity from regulation. Changes to protein expression in Aurora A, a mitotic Ser/Thr kinase, are associated with the development of several human cancers, but the effects of somatic cancer-associated mutations have not been determined. In this study we show that Aurora A kinase activity is altered in different ways in three somatic cancer-associated mutations located within the catalytic domain; Aurora A(V174M) shows constitutively increased kinase activity, Aurora A(S155R) activity is decreased primarily due to misregulation, and Aurora A(S361*) activity is ablated due to loss of structural integrity. These alterations suggest vastly different mechanisms for the role of these three mutations in human cancer. We have further characterized the Aurora A(S155R) mutant protein, found that its reduced cellular activity and mislocalization are due to loss of interaction with TPX2, and deciphered the structural basis of the disruption at 2.5 A resolution. Previous studies have shown that disruption of the Aurora A/TPX2 interaction results in defective spindles that generate chromosomal abnormalities. In a panel of 40 samples from microsatellite instability-positive colon cancer patients, we found one example in which the tumor contained only Aurora A(S155R), whereas the normal tissue contained only wild-type Aurora A. We propose that the S155R mutation is an example of a somatic mutation associated with this tumor type, albeit at modest frequency, that could promote aneuploidy through the loss of regulated interactions between Aurora A and its protein partners.

Purpose Estimating familial colorectal cancer (CRC) risk is clinically important in being able to discriminate between high- and low-risk groups. To quantify familial CRC risks associated with mismatch repair (MMR) deficient and microsatellite stable (MSS) tumors, we analyzed 2,941 population-based cases of CRC. Patients and Methods MMR status in CRCs was established by testing for microsatellite instability (MSI). MUTYH status was assigned by screening for Y165C and G382D variants. Age-specific relative and absolute CRC risks in first-degree relatives (FDRs) were calculated, and the most likely genetic models of familial aggregation were derived. Results CRC risks in FDRs were strongly associated with MSI status (MSI, standardized incidence ratio [SIR] = 4.28, 95% CI, 3.51 to 5.17; MSS, SIR = 1.91, 95% CI, 1.73 to 2.11), early-onset disease (MSI patient age < 55 years, SIR = 10.96, 95% CI, 8.32 to 14.17; MSS patient age < 55 years, SIR = 2.3, 95% CI, 1.88 to 2.85), and having more than one affected FDR (MSI, SIR = 10.00, 95% CI, 7.74 to 12.72; MSS, SIR = 2.78, 95% CI, 2.18 to 3.48). The familial aggregation of CRC associated with MSI cancer was parsimonious with dominant model conferring a high CRC risk at early ages. Approximately 69% of the excess familial risk in FDRs can be ascribed to MSS CRC, and although the pattern of familial risk supports recessive susceptibility in addition to MUTYH, the absolute risk of CRC is at best modest. Conclusion The results from this analysis should enable an individual's risk of CRC to be more accurately estimated, thus maximizing the value of screening programs. Results also have utility in the design of genetic analyses to identify novel disease alleles.

We mapped a high-penetrance gene (CRAC1; also known as HMPS) associated with colorectal cancer (CRC) in the Ashkenazi population to a 0.6-Mb region on chromosome 15 containing SCG5 (also known as SGNE1), GREM1 and FMN1. We hypothesized that the CRAC1 locus harbored low-penetrance variants that increased CRC risk in the general population. In a large series of colorectal cancer cases and controls, SNPs near GREM1 and SCG5 were strongly associated with increased CRC risk (for rs4779584, P = 4.44 x 10(-14)).