Comparative mapping of the DiGeorge region in the dog and exclusion of linkage to inherited canine conotruncal heart defects.

Conotruncal defects (CTDs) of the heart are a frequent component of DiGeorge, velocardiofacial, or other syndromes caused by deletions of the human chromosome 22q11 region (HSA22q11). In addition, some human patients with isolated nonsyndromic CTDs have been reported to have deletions of this region. Taken together, these findings lead to the conclusion that deletions of an HSA22q11 locus or loci produce abnormalities in cardiac development leading to CTDs. A spontaneous model of isolated inherited conotruncal malformations occurs in the keeshond dog. We have previously shown in experimental matings that nonsyndromic CTDs in the keeshond are inherited in a manner consistent with a major underlying locus. In the studies described in this article we tested two hypotheses: (1) the region of HSA22q11 commonly deleted in DiGeorge and related syndromes is evolutionarily conserved in the dog, and (2) a locus in this region is linked to hereditary CTD in the keeshond. Two loci within the minimal DiGeorge critical region (MDGCR) and two loci that lie telomeric to the MDGCR, one of which is commonly deleted in DiGeorge patients, were mapped in the dog using a combination of linkage analysis and fluorescence in situ hybridization (FISH). The results confirm conserved synteny of the loci DGS-I, CTP, D22S788 (N41), and IGLC on the telomeric end of canine chromosome 26 (CFA26). The group of four syntenic gene loci, which spans a genetic distance of 2.5 cM is the first to be mapped to this small acrocentric canine chromosome and adds gene-associated polymorphic markers to the developing dog linkage map. Linkage of loci in this region to hereditary CTD in the keeshond was excluded.     

A novel locus for autosomal dominant nonsyndromic hearing loss (DFNA44) maps to chromosome 3q28–29

Hereditary non-syndromic sensorineural hearing loss (NSSHL) is a genetically highly heterogeneous group of disorders. Autosomal dominant forms account for up to 20% of cases. To date, 39 loci have been identified by linkage analysis of affected families that segregate NSSHL forms in the autosomal dominant mode (DFNA). Investigation of a large Spanish pedigree with autosomal dominant inheritance of bilateral and progressive NSSHL of postlingual onset excluded linkage to known DFNA loci and, in a subsequent genome-wide scan, the disorder locus was mapped to 3q28-29. A maximum two-point LOD score of 4.36 at theta=0 was obtained for marker D3S1601. Haplotype analysis placed the novel locus, DFNA44, within a 3-cM genetic interval defined by markers D3S1314 and D3S2418. Heteroduplex analysis and DNA sequencing of coding regions and exon/intron boundaries of two genes (CLDN16 and FGF12) in this interval did not reveal disease-causing mutations.     

Identification of genetic loci for basal cell nevus syndrome and inflammatory bowel disease in a single large pedigree

Basal Cell Nevus Syndrome (BCNS) is an autosomal dominant disease. PTCH1 gene mutations have been found responsible in many but not all pedigrees. Inflammatory Bowel Disease (IBD) is a complex genetic disorder, disproportionate in Ashkenazim, and characterized by chronic intestinal inflammation. We revisited a large Ashkenazim pedigree, first reported in 1968, with multiple diagnoses of BCNS and IBD, and with a common genetic cause for both disorders proposed. We expanded the pedigree to four generations and performed a genome-wide linkage study for BCNS and IBD traits. Twelve members with BCNS, seven with IBD, five with both diagnoses and eight unaffected were genotyped. Both non-parametric (GENEHUNTER 2.1) and parametric (FASTLINK) linkage analyses were performed and a validation through simulation was performed. BCNS linked to chromosome 9q22 (D9S1120) just proximal to the PTCH1 gene (NPL=3.26, P=0.003; parametric two-point LOD=2.4, parametric multipoint LOD=3.7). Novel IBD linkage evidence was observed at chromosome 1p13 (D1S420, NPL 3.92, P=0.0047; parametric two-point LOD=1.9). Linkage evidence was also observed to previously reported IBD loci on 4q, (D4S2623, NPL 3.02, P=0.012; parametric two-point LOD=2.15), 10q23 (D10S1225 near DLG5, NPL 3.33, P=0.0085; parametric two-point LOD=1.3), 12 overlapping the IBD2 locus (D12S313, NPL 2.6, P=0.018; parametric two-point LOD=1.52), and 7q (D7S510 and D7S3046, NPL 4.06, P=0.0035; parametric two-point LOD=2.18). In this pedigree affected by both BCNS and IBD, the two traits and their respective candidate genetic loci segregate independently; BCNS maps to the PTCH1 gene and IBD maps to several candidate regions, mostly overlapping previously observed IBD loci.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.Carolien I. Panhuysen and Amir Karban contributed equally to this work     

Genomewide search in familial Paget disease of bone shows evidence of genetic heterogeneity with candidate loci on chromosomes 2q36, 10p13, and 5q35

Paget disease of bone (PDB) is a common disorder characterized by focal abnormalities of increased and disorganized bone turnover. Genetic factors are important in the pathogenesis of PDB, and previous studies have shown that the PDB-like bone dysplasia familial expansile osteolysis is caused by activating mutations in the TNFRSF11A gene that encodes receptor activator of nuclear factor kappa B (RANK); however, linkage studies, coupled with mutation screening, have excluded involvement of RANK in the vast majority of patients with PDB. To identify other candidate loci for PDB, we conducted a genomewide search in 319 individuals, from 62 kindreds with familial PDB, who were predominantly of British descent. The pattern of inheritance in the study group as a whole was consistent with autosomal dominant transmission of the disease. Parametric multipoint linkage analysis, under a model of heterogeneity, identified three chromosomal regions with LOD scores above the threshold for suggestive linkage. These were on chromosomes 2q36 (LOD score 2.7 at 218.24 cM), 5q35 (LOD score 3.0 at 189.63 cM), and 10p13 (LOD score 2.6 at 41.43 cM). For each of these loci, formal heterogeneity testing with HOMOG supported a model of linkage with heterogeneity, as opposed to no linkage or linkage with homogeneity. Two-point linkage analysis with a series of markers from the 5q35 region in another large kindred with autosomal dominant familial PDB also supported linkage to the candidate region with a maximum LOD score of 3.47 at D5S2034 (187.8 cM). These data indicate the presence of several susceptibility loci for PDB and identify a strong candidate locus for the disease, on chromosome 5q35.     

Linkage mapping of the locus responsible for congenital multiple ocular defects in cattle on bovine Chromosome 18

Congenital multiple ocular defects (MOD) in Japanese black cattle is a hereditary ocular disorder with an autosomal recessive manner of inheritance, showing developmental defects of the lens, retina, and iris, persistent embryonic eye vascularization, and microphthalmia. In the present study, we mapped the locus responsible for the disorder by linkage analysis using 240 microsatellite markers covering the entire bovine genome and an inbred pedigree obtained from commercial herds. The linkage analysis demonstrated a significant linkage between the disorder locus and markers on the proximal region of bovine Chromosome (BTA) 18 with the maximum LOD score of 5.1. Homozygosity mapping using the haplotype of the linked markers further refined the critical region. The results revealed the localization of the locus responsible for MOD in an approximately 6.6-cM region of BTA18. Comparison of published linkage and radiation hybrid (RH) maps of BTA18 with its evolutionary ortholog, human Chromosome (HSA) 16, revealed several potential candidate genes for the disorder including the MAF and FOXC2 genes.     

A single major-gene defect underlying cardiac conotruncal malformations interferes with myocardial growth during embryonic development: studies in the CTD line of keeshond dogs.

The common forms of isolated congenital heart disease are usually not inherited in a Mendelian pattern, and most are considered multifactorial threshold traits. A large subset consisting of a group of malformations of the ventricular outflow region, termed "conotruncal defects" (CTDs), include subarterial ventricular septal defects, tetralogy of Fallot, and persistent truncus arteriosus. Similar aggregations of CTDs have been reported in human families and in the keeshond breed of dog. The results of our early breeding experiments utilizing noninbred keeshonds were not consistent with any hypothesis of a fully penetrant monogenic inheritance. Here we report a recent series of genetic and embryologic studies conducted after more than 10 generations of selective inbred matings between affected-CTD-line dogs. The results are now consistent with a defect at a single autosomal locus, the Mendelian pattern of transmission having been obscured prior to selective inbreeding by genetic background. On the basis of morphometric embryologic studies, the mutant CTD allele causes conotruncal malformations in homozygous animals by interfering with myocardial growth in the conotruncus during the critical window when the conotruncal cushions fuse to form the conotruncal septum.     

Linkage analysis of a large African family segregating stuttering suggests polygenic inheritance

We describe a pedigree of 71 individuals from the Republic of Cameroon in which at least 33 individuals have a clinical diagnosis of persistent stuttering. The high concentration of stuttering individuals suggests that the pedigree either contains a single highly penetrant gene variant or that assortative mating led to multiple stuttering-associated variants being transmitted in different parts of the pedigree. No single locus displayed significant linkage to stuttering in initial genome-wide scans with microsatellite and SNP markers. By dividing the pedigree into five subpedigrees, we found evidence for linkage to previously reported loci on 3q and 15q, and to novel loci on 2p, 3p, 14q, and a different region of 15q. Using the two-locus mode of Superlink, we showed that combining the recessive locus on 2p and a single-locus additive representation of the 15q loci is sufficient to achieve a two-locus score over 6 on the entire pedigree. For this 2p + 15q analysis, we show LOD scores ranging from 4.69 to 6.57, and the scores are sensitive to which marker is chosen for 15q. Our findings provide strong evidence for linkage at several loci.     

Novel locus for autosomal dominant hereditary spastic paraplegia, on chromosome 8q.

Hereditary spastic paraplegia (HSP) is a clinically and genetically heterogeneous group of disorders characterized by insidiously progressive spastic weakness in the legs. Genetic loci for autosomal dominant HSP exist on chromosomes 2p, 14q, and 15q. These loci are excluded in 45% of autosomal dominant HSP kindreds, indicating the presence of additional loci for autosomal dominant HSP. We analyzed a Caucasian kindred with autosomal dominant HSP and identified tight linkage between the disorder and microsatellite markers on chromosome 8q (maximum two-point LOD score 5.51 at recombination fraction 0). Our results clearly establish the existence of a locus for autosomal dominant HSP on chromosome 8q23-24. Currently this locus spans 6.2 cM between D8S1804 and D8S1774 and includes several potential candidate genes. Identifying this novel HSP locus on chromosome 8q23-24 will facilitate discovery of this HSP gene, improve genetic counseling for families with linkage to this locus, and extend our ability to correlate clinical features with different HSP loci.     

RXRA and HSPA5 map to the telomeric end of dog chromosome 9

Previous results showed that loci from human chromosome 17q (HSA17q) map to the centromeric two-thirds of dog chromosome 9 (CFA9). In these studies fluorescence in situ hybridization (FISH) using a human total chromosome 17 painting probe, indicated that the telomeric one-third of CFA9 must have homology to one or more human chromosomes other than HSA17. Here we report that this distal part of CFA9 contains a segment syntenic to the telomeric end of HSA9q and mouse chromosome 2 (MMU2). The gene loci encoding retinoid X receptor, alpha (RXRA) and heat shock protein 5 (HSPA5 or GRP78), which are found on HSA9q34 and MMU2, occupy a region on CFA9 distal to NF1 and CRYBA1. FISH of a canine specific genomic cosmid clone for RXRA demonstrated the more telomeric localization of this locus to NF1 on CFA9. A linkage map developed for the distal region of CFA9 included: NF1-(2·7 CM )-CRYBA1-(6·5 CM )-RXRA-(22 CM )-HSPA5. The next best order, RXRA-NF1-CRYBA1-HSPA5 with a difference in the log odds of 1·43 does not correspond to our findings with FISH. The most probable map order places HSPA5 distal to RXRA on CFA9 whereas in humans it lies centromeric of RXRA on HSA9q34.     

Genomewide Scan of Multiple Sclerosis in Finnish Multiplex Families

Multiple sclerosis (MS) is a neurological, demyelinating disorder with a putative autoimmune etiology. It is thought to be a multifactorial disease with a complex mode of inheritance. Here we report the results of a two-stage genomewide scan for loci predisposing to MS. The first stage of the screen, with a low-resolution map, was performed in a selection of 16 pedigrees collected from an isolated Finnish population. Multipoint, non-parametric linkage analysis of the 328 markers did not reveal statistically significant results. However, 10 slightly interesting regions (P = .1-.15) emerged, including our previous findings of the HLA complex on 6p21 and a putative locus on 5p14-p12. Eight of these novel regions were further analyzed by use of denser marker maps, in the second stage of the scan. For the chromosomal regions 4cen, 11tel, and 17q, the statistical significance increased, but not conclusively; for 2q32 and 10q21, the statistical significance did not change. Accordingly, genotyping of the high-density markers in these regions was performed, and the data were analyzed by use of two-point, parametric linkage analysis using the complete pedigree information of the 21 Finnish multiplex families. We detected suggestive evidence for a predisposing locus on chromosomal region 17q22-q24. Several markers on 17q22-q24 yielded positive LOD scores, with the maximum LOD score (Zmax) occurring with D17S807 (Zmax = 2.8, theta = .04; dominant model). Interestingly, a suggestive linkage between MS and the markers on 17q22-q24 was also revealed by a recent genomewide scan in MS families from the United Kingdom.     

A susceptibility locus for bipolar affective disorder on chromosome 4q35.

Bipolar affective disorder (BAD) affects approximately 1% of the population and shows strong heritability. To identify potential BAD susceptibility loci, we undertook a 15-cM genome screen, using 214 microsatellite markers on the 35 most informative individuals of a large, statistically powerful pedigree. Data were analyzed by parametric two-point linkage methods under several diagnostic models. LOD scores >1.00 were obtained for 21 markers, with four of these >2.00 for at least one model. The remaining 52 individuals in the family were genotyped with these four markers, and LOD scores remained positive for three markers. A more intensive screen was undertaken in these regions, with the most positive results being obtained for chromosome 4q35. Using a dominant model of inheritance with 90% maximum age-specific penetrance and including bipolar I, II, schizoaffective/mania, and unipolar individuals as affected, we obtained a maximum two-point LOD score of 2.20 (theta = .15) at D4S1652 and a maximum three-point LOD score of 3.19 between D4S408 and D4S2924. Nonparametric analyses further supported the presence of a locus on chromosome 4q35. A maximum score of 2.62 (P=.01) was obtained between D4S1652 and D4S171 by use of the GENEHUNTER program, and a maximum score of 3.57 (P=.0002) was obtained at D4S2924 using the affected pedigree member method. Analysis of a further 10 pedigrees suggests the presence of this locus in at least one additional family, indicating a possible predisposing locus and not a pedigree-specific mutation. Our results suggest the presence of a novel BAD susceptibility locus on chromosome 4q35.     

Genomewide linkage scan for schizophrenia susceptibility loci among Ashkenazi Jewish families shows evidence of linkage on chromosome 10q22

Previous linkage studies in schizophrenia have been discouraging due to inconsistent findings and weak signals. Genetic heterogeneity has been cited as one of the primary culprits for such inconsistencies. We have performed a 10-cM autosomal genomewide linkage scan for schizophrenia susceptibility regions, using 29 multiplex families of Ashkenazi Jewish descent. Although there is no evidence that the rate of schizophrenia among the Ashkenazim differs from that in other populations, we have focused on this population in hopes of reducing genetic heterogeneity among families and increasing the detectable effects of any particular locus. We pursued both allele-sharing and parametric linkage analyses as implemented in Genehunter, version 2.0. Our strongest signal was achieved at chromosome 10q22.3 (D10S1686), with a nonparametric linkage score (NPL) of 3.35 (genomewide empirical P=.035) and a dominant heterogeneity LOD score (HLOD) of 3.14. Six other regions gave NPL scores >2.00 (on chromosomes 1p32.2, 4q34.3, 6p21.31, 7p15.2, 15q11.2, and 21q21.2). Upon follow-up with an additional 23 markers in the chromosome 10q region, our peak NPL score increased to 4.27 (D10S1774; empirical P=.00002), with a 95% confidence interval of 12.2 Mb for the location of the trait locus (D10S1677 to D10S1753). We find these results encouraging for the study of schizophrenia among Ashkenazi families and suggest further linkage and association studies in this chromosome 10q region.     

A locus for autosomal dominant accessory auricular anomaly maps to 14q11.2–q12

Accessory auricular anomaly is a small excrescence of skin that contains elastic cartilage on different regions of the helix and the face. Previous work has shown that the genetic trait of some patients with the isolated symptom of accessory auricular anomaly is autosomal dominant. To map the gene for autosomal dominant accessory auricular anomaly (ADAAA), we investigated a Chinese family with 11 affected individuals. We performed linkage analysis with microsatellite markers spanning the whole human-genome in the family. The inheritance pattern of the ADAAA family was autosomal dominant with complete penetrance. Two-point linkage analysis revealed significant maximum LOD scores of 4.20(D14S990 and D14S264, sita = 0) in the family. Haplotype construction and multipoint linkage analysis also confirmed the locus and defined the isolated ADAAA locus to a 9.84 cM interval between the markers D14S283 and D14S297. Our study assigned an isolated ADAAA locus to 14q11.2–q12. This is the first ADAAA locus reported to date.Y. Yang and J. Guo contribute to this work equally.     

Genomewide linkage scan for split-hand/foot malformation with long-bone deficiency in a large Arab family identifies two novel susceptibility loci on chromosomes 1q42.2-q43 and 6q14.1

Split-hand/foot malformation with long-bone deficiency (SHFLD) is a rare, severe limb deformity characterized by tibia aplasia with or without split-hand/split-foot deformity. Identification of genetic susceptibility loci for SHFLD has been unsuccessful because of its rare incidence, variable phenotypic expression and associated anomalies, and uncertain inheritance pattern. SHFLD is usually inherited as an autosomal dominant trait with reduced penetrance, although recessive inheritance has also been postulated. We conducted a genomewide linkage analysis, using a 10K SNP array in a large consanguineous family (UR078) from the United Arab Emirates (UAE) who had disease transmission consistent with an autosomal dominant inheritance pattern. The study identified two novel SHFLD susceptibility loci at 1q42.2-q43 (nonparametric linkage [NPL] 9.8, P=.000065) and 6q14.1 (NPL 7.12, P=.000897). These results were also supported by multipoint parametric linkage analysis. Maximum multipoint LOD scores of 3.20 and 3.78 were detected for genomic locations 1q42.2-43 and 6q14.1, respectively, with the use of an autosomal dominant mode of inheritance with reduced penetrance. Haplotype analysis with informative crossovers enabled mapping of the SHFLD loci to a region of approximately 18.38 cM (8.4 Mb) between single-nucleotide polymorphisms rs1124110 and rs535043 on 1q42.2-q43 and to a region of approximately 1.96 cM (4.1 Mb) between rs623155 and rs1547251 on 6q14.1. The study identified two novel loci for the SHFLD phenotype in this UAE family.     

High-density genome scan in Crohn disease shows confirmed linkage to chromosome 14q11-12

Epidemiological studies have shown that genetic factors contribute to the pathogenesis of the idiopathic inflammatory bowel diseases (IBD), Crohn disease (CD) and ulcerative colitis (UC). Recent genome scans and replication studies have identified replicated linkage between CD and a locus on chromosome 16 (the IBD1 locus), replicated linkage between IBD (especially UC) and a locus on chromosome 12q (the IBD2 locus), and replicated linkage between IBD (especially CD) and a locus on chromosome 6p (the IBD3 locus). Since the estimated locus-specific lambdas values for the regions of replicated linkage do not account for the overall lambdas in CD, and since the published genome scans in IBD show at least nominal evidence for linkage to regions on all but two chromosomes, we performed an independent genome scan using 751 microsatellite loci in 127 CD-affected relative pairs from 62 families. Single-point nonparametric linkage analysis using the GENEHUNTER-PLUS program shows evidence for linkage to the adjacent D14S261 and D14S283 loci on chromosome 14q11-12 (LOD = 3.00 and 1.70, respectively), and the maximal multipoint LOD score is observed at D14S261 (LOD = 3.60). In the multipoint analysis, nominal evidence for linkage (P<.05) is observed near D2S117 (LOD = 1.25), near D3S3045 (LOD = 1.31), between D7S40 and D7S648 (LOD = 0.91), and near D18S61 (LOD = 1.15). Our finding of significant linkage to D14S261 and the finding of suggestive linkage to the same locus in an independent study (multipoint LOD = 2.8) satisfies criteria for confirmed linkage, so we propose that the region of interest on chromosome 14q11-12 should be designated the IBD4 locus.     

A Chinese Benign Adult Familial Myoclonic Epilepsy Pedigree Suggesting Linkage to Chromosome 5p15.31–p15.1

Benign adult familial myoclonic epilepsy (BAFME) has been mapped to chromosome 8q23.3–q24.1, 2p11.1–q12.1, 5p15.31–p15.1, and 3q26.32–3q28, in Japanese, Italian, Thai, and French pedigrees, respectively. Recently, we investigated a Chinese BAFME family. Clinical and electrophysiological studies revealed that nine individuals were affected with BAFME. We aimed to establish the causative gene for this pedigree. We genotyped 17 microsatellite markers covering the four previously identified chromosome regions and performed linkage analyses. The linkage analysis data showed that the LOD score was 2.80 for D5S486 at no recombination. This suggested linkage to 5p15.31–p15.1 and excluded linkage to the other three loci (LOD score <0 at no recombination). Our study suggests that the causative gene responsible for BAFME in the Chinese pedigree may be located on chromosome 5p15.31–p15.1.     

A locus for autosomal dominant "pure" hereditary spastic paraplegia maps to chromosome 19q13

Genetic loci for autosomal dominant pure hereditary spastic paraplegia (ADPHSP) have been mapped to chromosomes 2p, 8q, 12q, 14q, and 15q. We undertook a genomewide linkage screen of a large family with ADPHSP, for which linkage at all previously identified ADPHSP loci was excluded. Analysis of markers on chromosome 19q gave a peak pairwise LOD score of 3.72 at D19S420, allowing assignment of a novel ADPHSP locus (which we have termed "SPG12") to this region. Haplotype construction and analysis of recombination events narrowed the SPG12 locus to a 16.1-cM region between markers D19S868 and D19S902.     

Genome scans provide evidence for low-HDL-C loci on chromosomes 8q23, 16q24.1-24.2, and 20q13.11 in Finnish families

We performed a genomewide scan for genes that predispose to low serum HDL cholesterol (HDL-C) in 25 well-defined Finnish families that were ascertained for familial low HDL-C and premature coronary heart disease. The potential loci for low HDL-C that were identified initially were tested in an independent sample group of 29 Finnish families that were ascertained for familial combined hyperlipidemia (FCHL), expressing low HDL-C as one component trait. The data from the previous genome scan were also reanalyzed for this trait. We found evidence for linkage between the low-HDL-C trait and three loci, in a pooled data analysis of families with low HDL-C and FCHL. The strongest statistical evidence was obtained at a locus on chromosome 8q23, with a two-point LOD score of 4.7 under a recessive mode of inheritance and a multipoint LOD score of 3.3. Evidence for linkage also emerged for loci on chromosomes 16q24.1-24.2 and 20q13.11, the latter representing a recently characterized region for type 2 diabetes. Besides these three loci, loci on chromosomes 2p and 3p showed linkage in the families with low HDL-C and a locus on 2ptel in the families with FCHL.     

The genetics of reading disability in an often excluded sample: novel loci suggested for reading disability in rolandic epilepsy

Background

Reading disability (RD) is a common neurodevelopmental disorder with genetic basis established in families segregating “pure” dyslexia. RD commonly occurs in neurodevelopmental disorders including Rolandic Epilepsy (RE), a complex genetic disorder. We performed genomewide linkage analysis of RD in RE families, testing the hypotheses that RD in RE families is genetically heterogenenous to pure dyslexia, and shares genetic influences with other sub-phenotypes of RE.

Methods

We initially performed genome-wide linkage analysis using 1000 STR markers in 38 US families ascertained through a RE proband; most of these families were multiplex for RD. We analyzed the data by two-point and multipoint parametric LOD score methods. We then confirmed the linkage evidence in a second US dataset of 20 RE families. We also resequenced the SEMA3C gene at the 7q21 linkage locus in members of one multiplex RE/RD pedigree and the DISC1 gene in affected pedigrees at the 1q42 locus.

Results

In the discovery dataset there was suggestive evidence of linkage for RD to chromosome 7q21 (two-point LOD score 3.05, multipoint LOD 3.08) and at 1q42 (two-point LOD 2.87, multipoint LOD 3.03). Much of the linkage evidence at 7q21 derived from families of French-Canadian origin, whereas the linkage evidence at 1q42 was well distributed across all the families. There was little evidence for linkage at known dyslexia loci. Combining the discovery and confirmation datasets increased the evidence at 1q42 (two-point LOD = 3.49, multipoint HLOD = 4.70), but decreased evidence at 7q21 (two-point LOD = 2.28, multipoint HLOD  = 1.81), possibly because the replication sample did not have French Canadian representation.

Discussion

Reading disability in rolandic epilepsy has a genetic basis and may be influenced by loci at 1q42 and, in some populations, at 7q21; there is little evidence of a role for known DYX loci discovered in “pure” dyslexia pedigrees. 1q42 and 7q21 are candidate novel dyslexia loci.