Showing papers by "Jonathan L. Haines published in 2001"

Partial and generalized epilepsy with febrile seizures plus and a novel SCN1A mutation

Abstract: Background: Generalized epilepsy with febrile seizures plus (GEFS+) is an autosomal dominant syndrome characterized by febrile seizures (FS) and a variety of afebrile generalized seizure types. GEFS+ has previously been linked to mutations in two genes encoding the voltage-gated sodium channel α-subunit ( SCN1A ) and β1-subunit ( SCN1B ). We studied a large family with FS and partial as well as generalized seizure types. Methods: All but two living affected family members were interviewed and examined. Information on deceased affected family members was sought. EEG for 11 affected family members and one unaffected family member were obtained. Genetic linkage analysis and mutation screening of SCN1A were performed on blood samples from 16 affected individuals and their first-degree relatives. Results: There were 27 affected family members; 18 were alive at the time of the study. All affected family members had FS; seven had FS only, and 19 also had afebrile seizures. Eleven individuals continued to have FS beyond 6 years of age. FS were complex in 12 family members, usually with prolonged duration. The index patient had right temporal lobe epilepsy and hippocampal sclerosis. Four other patients had strong historical evidence of temporal lobe epilepsy, and three others had nonlocalizing evidence of partial epilepsy. Pedigree analysis indicated autosomal dominant transmission. All affected individuals who were tested and one asymptomatic individual had a sodium channel mutation of SCN1A , an A→C transversion at nucleotide 3809 resulting in the substitution of lysine 1270 by threonine in the D3/S2 segment (designated as K1270T). Conclusions: Our findings indicate that partial epilepsy preceded by FS can be associated with sodium channel mutations and may represent a variant of GEFS+.

Incorporating language phenotypes strengthens evidence of linkage to autism

Abstract: We investigated the effect of incorporating information about proband and parental structural language phenotypes into linkage analyses in the two regions for which we found the highest signals in our first-stage affected sibling pair genome screen: chromosomes 13q and 7q. We were particularly interested in following up on our chromosome 7q finding in light of two prior reports of linkage of this region to developmental language disorder, since one of the diagnostic criteria for autism is absent or abnormal language development. We hypothesized that if the language phenotype were genetically relevant to linkage at the chromosome 7q locus, then incorporating parents phenotypes would increase the signal at that locus, and most of the signal would originate from the subset of families in which both probands had severe language delay. The results support these hypotheses. The linkage signals we obtained on chromosome 7q as well as at least one signal on chromosome 13q are mainly attributable to the subgroup of families in which both probands had language delay. This became apparent only when the parents' history of language-related difficulties was also incorporated into the analyses. Although based on our data, we were not able to distinguish between epistasis or heterogeneity models, we tentatively concluded that there may be more than one autism susceptibility locus related to language development.

A meta-analysis of genomic screens in multiple sclerosis

Abstract: We combined the raw genotyping data from three large multiple sclerosis genome screens and performed a global meta-analysis in order to compare and summarize the linkage results from the different studies. In alphabetical order, the screens provided data from 442 markers typed in 52 multiplex families with a total of 133 affected individuals (the American screen), 314 markers typed in 128 families with 264 affecteds (the British screen) and 257 markers typed in 61 families with a total of 139 affected subjects (the Canadian screen). Multipoint analysis of these data was performed using the GENEHUNTER program. The highest non-parametric linkage (NPL) score in the meta-analysis was observed on chromosome 17q11 (NPL score 2.58), although this score falls short of genome-wide significance. A total of eight regions had NPL scores greater than 2.0. One of the regions with an NPL score greater than 2.0 was the HLA region on chromosome 6p21 (NPL=2.2). This region is known, from association studies, to be involved in MS susceptibility, but the modest linkage result observed here suggests the encoded susceptibility effect is not large compared with the high familial recurrence in MS (lambda approximately 20). Overall, our linkage results suggest that MS is likely to be multigenic in its genetic susceptibility.

PTPRC (CD45) is not associated with the development of multiple sclerosis in U.S. patients.

Abstract: A C-->G nucleotide transition in exon 4 of PTPRC (encoding protein-tyrosine phosphatase receptor-type C, also known as CD45) was recently reported to be genetically associated with the development of multiple sclerosis (MS). We performed an extensive evaluation of this polymorphism using large family-based and case-control comparisons. Overall, we observed no evidence of genetic association between the PTPRC polymorphism and MS susceptibility or disease course.

A Recurrent RNA-Splicing Mutation in the SEDL Gene Causes X-Linked Spondyloepiphyseal Dysplasia Tarda

Abstract: Spondyloepiphyseal dysplasia tarda (SEDL) is a genetically heterogeneous disorder characterized by mild-to-moderate short stature and early-onset osteoarthritis. Both autosomal and X-linked forms have been described. Elsewhere, we have reported the identification of the gene for the X-linked recessive form, which maps to Xp22.2. We now report characterization of an exon-skipping mutation (IVS3+5G→A at the intron 3 splice-donor site) in two unrelated families with SEDL. Using reverse transcriptase (RT)–PCR, we demonstrated that the mutation resulted in elimination of the first 31 codons of the open reading frame. The mutation was not detected in 120 control X chromosomes. Articular cartilage from an adult who had SEDL and carried this mutation contained chondrocytes with abundant Golgi complexes and dilated rough endoplasmic reticulum (ER). RT-PCR experiments using mouse/human cell hybrids revealed that the SEDL gene escapes X inactivation. Homologues of the SEDL gene include a transcribed retropseudogene on chromosome 19, as well as expressed genes in mouse, rat, Drosophila melanogaster Caenorhabditis elegans, and Saccharomyces cerevisiae. The latter homologue, p20, has a putative role in vesicular transport from ER to Golgi complex. These data suggest that SEDL mutations may perturb an intracellular pathway that is important for cartilage homeostasis.

Linkage and association analysis of chromosome 19q13 in multiple sclerosis

Abstract: Multiple sclerosis (MS) is an autoimmune neurological disorder with a complex etiology. Sibling risk, twin, and adoption studies have demonstrated that genes play a vital role in susceptibility to MS. Numerous association and linkage studies have implicated the major histocompatibility complex (MHC) as one component of the genetic etiology, but additional loci remain to be identified. Genomic screens have suggested over 50 regions that might harbor these genes, but there has been little agreement between studies. The one region suggested by all four screens resides within chromosome 19q13. Allelic associations with several markers in this region have also been described. This region has now been examined in detail in an expanded dataset of MS families from the United States. Genetic linkage and association were tested with multiple markers in this region using both parametric and non-parametric analyses. Additional support for an MS susceptibility locus was observed, primarily in families with the MS-associated HLA-DR2 allele. While consistent, this effect appears to be modest with a maximum λS=1.47, probably representing no more than 10% of the overall genetic effect in MS.