Genomic cloning and localization by FISH and linkage analysis of the human gene encoding the primary subunit NMDAR1 (GRIN1) of the NMDA receptor channel

Elevated common variant genetic risk for tourette syndrome in a densely-affected pedigree

Tourette syndrome (TS) is a highly heritable neuropsychiatric disorder with complex patterns of genetic inheritance. Recent genetic findings in TS have highlighted both numerous common variants with small effects and a few rare variants with moderate or large effects. Here we searched for genetic causes of TS in a large, densely-affected British pedigree using a systematic genomic approach. This pedigree spans six generations and includes 122 members, 85 of whom were individually interviewed, and 53 of whom were diagnosed as "cases" (consisting of 28 with definite or probable TS, 20 with chronic multiple tics [CMT], and five with obsessive-compulsive behaviors [OCB]). A total of 66 DNA samples were available (25 TS, 15 CMT, 4 OCB cases, and 22 unaffecteds) and all were genotyped using a dense single nucleotide polymorphism (SNP) array to identify shared segments, copy number variants (CNVs), and to calculate genetic risk scores. Eight cases were also whole genome sequenced to test whether any rare variants were shared identical by descent. While we did not identify any notable CNVs, single nucleotide variants, indels or repeat expansions of near-Mendelian effect, the most distinctive feature of this family proved to be an unusually high load of common risk alleles for TS. We found that cases within this family carried a higher load of TS common variant risk similar to that previously found in unrelated TS cases. Thus far, the strongest evidence from genetic data for contribution to TS risk in this family comes from multiple common risk variants rather than one or a few variants of strong effect.

The Gilles de la Tourette syndrome: a principal component factor analytic study of a large pedigree

BACKGROUND

The genetics and phenotypes of Gilles de la Tourette syndrome are complicated. Once indicated to be inherited as a single major autosomal dominant condition, several areas of interest on many chromosomes and one gene have been identified for Gilles de la Tourette syndrome, but no results have been replicated. Factor analytic studies suggest that there are more than one Gilles de la Tourette syndrome phenotype and it is not a unitary condition.

OBJECTIVE

To characterize Gilles de la Tourette syndrome phenotypes in a group of individuals who underwent a complete genome scan.

METHODS

We studied 85 members of a multiply affected multigenerational kindred, of whom 69 displayed Gilles de la Tourette syndrome-related symptoms (tics, obsessive-compulsive behaviours, obsessive-compulsive symptoms, attention deficit hyperactivity symptoms), using first a hierarchical cluster analysis followed by a principal component factor analysis.

RESULTS

Three significant factors resulted from our analysis, accounting for approximately 42% of the symptomatic variance: Factor 1 (predominantly 'pure tics'), Factor 2 (predominantly 'attention deficit hyperactivity disorder and aggressive behaviours') and Factor 3 (predominantly 'depression-anxiety-obsessional symptoms and self-injurious behaviours'). Different kinds of tics occurred in all three factors. Only frowning/raising eyebrows and sniffing/smelling loaded significantly on both Factors 1 and 3.

CONCLUSION

Our results give further evidence that the genetics of Gilles de la Tourette syndrome is complex and suggest that Gilles de la Tourette syndrome is not a unitary condition, thus confirming the results of earlier studies which have described several Gilles de la Tourette syndrome phenotypes. Although a genome scan on the pedigree reported three areas of interest and the present study found three factors, further studies would have to be undertaken to elucidate whether the three factors 'mapped' with the genetic data. Possible reasons for our findings and suggestions for future research are discussed.

Linkage of the gene for an autosomal dominant form of juvenile amyotrophic lateral sclerosis to chromosome 9q34

We performed genetic mapping studies of an 11-generation pedigree with an autosomal dominant, juvenile-onset motor-systems disease. The disorder is characterized by slow progression, distal limb amyotrophy, and pyramidal tract signs associated with severe loss of motor neurons in the brain stem and spinal cord. The gene for this disorder, classified as a form of juvenile amyotrophic lateral sclerosis (ALS), is designated "ALS4." We performed a genomewide search and detected strong evidence for linkage of the ALS4 locus to markers from chromosome 9q34. The highest LOD score (Z) was obtained with D9S1847 (Z=18.8, recombination fraction of .00). An analysis of recombinant events identified D9S1831 and D9S164 as flanking markers, on chromosome 9q34, that define an approximately 5-cM interval that harbors the ALS4 gene. These results extend the degree of heterogeneity within familial ALS syndromes, and they implicate a gene on chromosome 9q34 as critical for motor-neuron function.

Comparative mapping of 50 human chromosome 9 loci in the laboratory mouse

We have set out to produce a comprehensive comparative map between human chromosome 9 (HSA9) and the laboratory mouse. The mouse homologues of 50 loci that were known to map to HSA9 were mapped by interspecific backcross linkage analysis. Ten loci from the short arm of HSA9 were mapped, and 40 from HSA9q, with 24 markers coming from the HSA9q33-q34 region--a part of the chromosome known to be very gene rich. Fifteen new assignments have been made--Ak3, Ctsl, Cntfr, C8g, D2H9S46E, Eng, Gcnt1, Irebp, Pappa, Ptgds, Snf212, Tal2, Tmod, Vav2, and Vldlr, the human homologues of which all map to HSA9. In addition, the assignment of Snf212 and Vldlr to MMU19 has defined a new region of synteny between the proximal portion of the short arm of HSA9 and the mouse.