C55 GENOME WIDE ASSOCIATION STUDIES IN COMPLEX DISEASES: LESSONS FOR ALS
HARDY J
Department of Molecular Neuroscience and Reta Lila Weston Laboratories, Institute of Neurology, UCL, London, UK
Email address for correspondence: [email protected]
No abstract received.
C56 WHOLE GENOME ASSOCIATION STUDY REVEALS GENETIC VARIANTS THAT MODIFY SURVIVAL IN SPORADIC AMYOTROPHIC LATERAL SCLEROSIS
LANDERS J1, MELKI J2, MEININGER V3, GLASS J4, VAN DEN BERG L5, VAN ES M5, SAPP P1, MCKENNA-YASEK D1, CHO TJ1, SHI L1, WILLS AM1, BROOM W1, RODRIGUEZ-LEYVA I6, LATHROP M7, PURCELL S8, AL-CHALABI A9, BROWN JR. R1
1Cecil B. Day Neuromuscular Research Laboratory, Charlestown, MA, United States, 2Hadassah University Hospital, Jerusalem, Israel, 3Hôpital de la Salpêtrière, Paris, France, 4Emory University, Atlanta, GA, United States, 5University Medical Center, Utrecht, Netherlands, 6Universidad Autonoma de San Luis Potosi, San Luis Potosi, Mexico, 7Institut Génomique, Evry, France, 8Massachusetts General Hospital, Boston, MA, United States, 9King's College London, United Kingdom
E-mail address for correspondence: [email protected]
Keywords: Amyotrophic Lateral Sclerosis; SNP; Whole Genome Association Study
Background: Amyotrophic lateral sclerosis is a degenerative disorder of motor neurons that typically develops in the sixth decade and is uniformly fatal, usually within five years. About 10% of ALS cases are dominantly inherited whereas sporadic ALS is thought to be multifactorial, with environmental, infectious and genetic etiologies.
Objectives: To identify genetic variants associated with susceptibility and phenotypes in sporadic ALS, we performed a genome-wide analysis of single nucleotide polymorphisms in ALS cases and controls.
Methods: In a set of 1829 sporadic ALS (SALS) cases and 2250 controls, we completed an unbiased analysis of ∼288,357 SNPs (1,176,208,203 genotypes) distributed across the genome. Genotypes were obtained from three sources in the USA (total 917 ALS, 912 controls) and three in Europe (904 ALS, 1346 controls) and analyzed as a single set of SALS cases and controls. Genotypes were used for the analysis of four phenotypes in SALS: susceptibility, site of onset, age of onset and survival of disease.
Results: From our study, we identified a SNP that yielded a genome-wide significant result that withstood Bonferroni correction (uncorrected and corrected p values of 1.84E-08 and 0.021) for association with survival (n = 1014). Homozygosity for the favorable allele conferred a 14.0 months survival advantage. No SNPs were significantly associated with risk of sporadic ALS, site of onset, or age of onset.
Conclusions: These findings support the view that genetic factors modify survival in ALS. In our view, the identification of a potential determinant of rate of progression of sporadic ALS is therefore promising; insights into this molecular pathway may provide new targets for therapies to slow this devastating disease.
C57 SCREENING FOR REPLICATION OF GENOME-WIDE ASSOCIATION SIGNALS IN THE IRISH AND POLISH ALS POPULATIONS
CRONIN S1, TOMIK B2, HARDIMAN O1, SLOWIK A2
1Beaumont Hospital, Dublin, Ireland, 2Jagiellonian University, Krakow, Poland
E-mail address for correspondence: [email protected]
Keywords: Genome wide study, DPP6, genetics
Background and Objectives: We recently reported a joint analysis of genome-wide data on 958 sporadic ALS (SALS) cases and 932 controls from Ireland and publicly available datasets from The Netherlands and US. The strongest pooled association was rs10260404 in the DPP6 gene. Here, we sought replication of joint analysis signals in both an expanded Irish and a Polish SALS cohort.
Methods: The study populations comprised an expanded Irish cohort (312 patients with SALS; 259 controls) and an additional Polish cohort (218 patients; 356 controls). Among 287,522 autosomal SNPs, 27 were commonly associated for the same allele at a p value below 0.1 in the Irish and US and below 0.05 in the larger Dutch set. These 27 SNPs were genotyped using KASPar assays. Allelic p values were computed using standard chi-squared statistics in PLINK.
Results: Eleven SNPs, including rs10260404, reached a final p value below 0.05 in the Irish. None of these showed association with SALS in the Polish cohort. Pooling of data from this study and the previous genome scans (1267 SALS; 1336 controls) did not identify any association reaching Bonferroni significance (p < 1.74×0 − 7) or of stronger significance than pooling the genome-wide data alone.
Conclusions: The present strategy did not reveal any consistently associated SNP across four populations. The results may be explained by population-specific differences or by the relatively low power of each included dataset. Future expansion of genome-wide SNP data will refine susceptibility loci for SALS both within and between populations.
C58 CLINICAL AND GENETIC PHENOTYPE OF 283 ALS FAMILIES
CORCIA P1, VALDMANIS P2, KHORIS J3, PRALINE J1, MORALES J3, PAGEOT N3, VOURC'H P4, ROULEAU G2, ANDRES C4, CAMU W3
1ALS Center, Tours, France, 2Center of Excellence in Neuromics, Montreal, Canada, 3ALS Center, Montpellier, France, 4INSERM U930, Tours, France
E-mail address for correspondence: [email protected]
Keywords: Familial ALS, Phenotype, SOD1 mutations
Background: Amyotrophic Lateral Sclerosis is the most frequent motor neuron disorder in adults. Almost 10% to 20% of ALS cases are familial (FALS). To date, in the literature, phenotypes of familial and sporadic forms are considered similar. However, it is frequently noted that FALS cases have an earlier age of onset and bulbar onset is rare. SOD1 mutations are supposed to account for at least 20% of FALS cases. However there are few large studies focused on phenotype analysis of FALS cases.
Objectives: To describe clinical and genetic phenotype of 283 French FALS, to determine whether they correspond to the model described in many studies: a dominant inheritance, an earlier onset, a rare bulbar onset and a longer duration.
Material and Methods: A FALS network has been developed in France since 1996 for collecting as exhaustively as possible the families in our country. To date, 283 families have been identified. We collected clinical characteristics: gender, age of onset, site of onset, ALS duration. For all the FALS cases a pedigree was drawn. When appropriate or needed we studied probands for SOD1 mutations. We separated, and then compared, the families according to the number of generations involved in the ALS process. In type I families (one generation), siblings or cousins had ALS. In type II, a parent and his offspring were affected (or uncle and nephew). In type III, ALS was distributed across three generations. We also compared, in type I and II, families with 2 ALS patients with those with more than two affected members (I+ and II + ).
Results: The group of 283 families was composed of 71 type I, 181 type II and 31 type III.
In type I FALS with 2 affected members (n = 62), sex ratio was 0.7, mean disease onset was 58yrs, 32% had bulbar onset, median ALS duration was 24.5 months, 5.5% of families carried SOD1 mutations. In type I+ families (n = 9), sex ratio was 1.3, mean disease onset was 58yrs, 48% had bulbar onset, median ALS duration was 35 months, 25% of families carried SOD1 mutations.
In type II FALS with 2 affected members (n = 132), sex ratio was 0.9, mean disease onset was 58yrs, 32% had bulbar onset, median ALS duration was 30 months, 7% of families carried SOD1 mutations. In type II+ (n = 49), sex ratio was 1, mean disease onset was 54yrs, 30% had bulbar onset, median ALS duration was 25.5 months, 19% of families carried SOD1 mutations.
In type III FALS (n = 31), sex ratio was 1.1, mean disease onset was 49yrs, 12% had bulbar onset, median ALS duration was 30 months, 29% of families carried SOD1 mutations.
Discussion:A small part of the FALS pedigrees (11%) are undoubtedly consistent with a dominant transmission. Their clinical and genetic phenotype well fit with the “FALS model” described previously. The vast majority of FALS cases (type I and II with 2 affected members, n = 184, 65%) are consistent with a complex genetic trait. However, as SOD1 mutations may be encountered in all three types, the percentage of families with a low penetrance cannot be strictly estimated. Nevertheless it seems that this percentage is not significantly high. New strategies for studying FALS cases are warranted.
C59 ANG K17I MUTATION SEGREGATING WITH AUTOSOMAL DOMINANT FAMILIAL AMYOTROPHIC LATERAL SCLEROSIS IN A LARGE DUTCH PEDIGREE
VAN ES M1, VAN VUGHT P1, DIEKSTRA F1, SCHELHAAS H2, BAAS F3, HENNEKAM E4, LINDHOUT D4, STRENGMAN E5, VELDINK J1, WOKKE J1, OPHOFF R5, VAN DEN BERG L1
1Department of Neurology, Rudolf Magnus Institute of Neuroscience, University Medical Center, Utrecht, Netherlands, 2Department of Neurology, Radboud University Medical Center, Nijmegen, Netherlands, 3Department of Neurogenetics, Academic Medical Center, Amsterdam, Netherlands, 4Department of Medical Genetics, University Medical Center, Utrecht, Netherlands, 5Department of Medical Genetics and Rudolf Magnus Institute of Neuroscience, University Medical Center Utrecht, Netherlands
E-mail address for correspondence: [email protected]
Keywords: ANG, FALS, ALS-FTDP
Background: Using a candidate gene approach mutations in ANG were identified in both sporadic and familial ALS patients, but not in a large cohort of healthy controls. Subsequent screens in other populations have also identified ANG mutations in ALS patients. However, these studies also found mutations in healthy controls, suggesting that not all ANG mutations are pathogenic.
Objectives: A study of familial ALS in The Netherlands was performed to: i) determine incidence and prevalence of FALS in The Netherlands, ii) to determine pattern of inheritance of FALS in each pedigree. All families were screened for mutations in SOD1 and ANG.
Methods: 39 families with ALS were included in the study. The index patient from each family was screened for mutations ANG. ANG mutation analysis was performed in all subjects as follows: DNA was amplified with PCR using primers: ANG_xn2_For, 5’ TGTTCTTGGGTCTACCACAC; ANG_xn2_Rev, 5’ AATGGAAGGCAAGGACAGC. Both forward and reverse strands were sequenced with the same primers used for PCR amplification. Sequence reaction products were purified using Sephadex (GE Healthcare) columns and run on an ABI 3730 automated sequencer. Traces were analyzed using ContigExpress from the Vector NTI Suite10 (Invitrogen). The K17I mutation was confirmed by repeating all sequencing steps in each individual using newly made DNA solutions from stock. A total of 275 ethnically matched control subjects were also screened for ANG mutations.
Results: In 39 probands from families with ALS, one mutation was identified in one proband (K17I). Subsequent analysis of the pedigree revealed an autosomal dominant pattern of inheritance. In this large family, DNA was available from 44 individuals (3 additional affected family members). The K17I mutation segregates with disease in this pedigree and was not found in 275 unrelated, healthy controls from The Netherlands. The I46V mutation was found one control.
Phenotypically, all affected family members had limb onset disease with rapid to average progression, respiratory involvement and minimal upper motor neuron signs. Interestingly, one patient had been diagnosed with Parkinson's disease 5 years prior to the onset of ALS and recently started to demonstrate altered behaviour, sexual disinhibition and problems performing complex tasks suggestive of FTD.
Discussion: Here, we present a large Dutch pedigree with an autosomal dominant form of familial ALS in which the K17I mutations clearly segregates with disease. Before ANG mutation screening is used diagnostically, as a target for drug therapy or transgenic animal models are created it is important to elucidate which mutations are pathogenic. This study provides evidence that the K17I mutation is pathogenic and may also be implicated in FTD and Parkinsonism.