Showing papers by "John B.J. Kwok published in 2007"
TL;DR: The SP phenotype in some PSEN1 AD pedigrees also appears to be associated with a delayed onset of dementia compared with affected individuals who present with dementia only, suggesting the existence of a protective factor in some individuals with SP.
Abstract: Pedigrees with familial Alzheimer's disease (FAD), caused by mutations in either the amyloid precursor protein (APP) or the presenilin 1 (PS1) or presenilin 2 (PS2) genes, show considerable phenotypic variability. Monogenic diseases typically exhibit variations in biological features, such as age of onset, severity, and multiple clinical and cellular phenotypes. This variation can be due to specific alleles of the disease gene, environmental effects, or modifier genes.
70 citations
TL;DR: The results demonstrate that the G2019S mutation carriers share the same ancestors who migrated to Australia originally from Europe and that other LRRK2 mutations (R1441H and A1442P) can be found in this population.
Abstract: We determined the prevalence of two common leucine-rich repeat kinase 2 (LRRK2) gene mutations in Australian patients with Parkinson's disease (PD). Of 830 affected patients, eight were heterozygous for the G2019S mutation, and two were heterozygous for the R1441H (4,322 G > A) mutation. In addition, one familial patient had a novel A1442P (4,324 G > C) mutation. Haplotype analysis showed that all LRRK2 G2019S-positive individuals carried the common founder haplotype 1 and a putative founder haplotype for the R1441H mutation carriers. Clinically, patients with LRRK2 mutations had typical levodopa responsive Parkinsonism with tremor being the commonest presenting feature. Patients with the G2019S mutation in our series had a similar age of onset of symptoms when compared with patients with other LRRK2 mutations or sporadic PD, although they were more likely to have a family history of PD (2.4% of Australian patients with familial PD and 0.3% of Australian patients with sporadic PD). Our results demonstrate that the G2019S mutation carriers share the same ancestors who migrated to Australia originally from Europe and that other LRRK2 mutations (R1441H and A1442P) can be found in this population.
37 citations
TL;DR: There is a need for a continuing search for genes that cause the phenotypic variation in Alzheimer's disease and spastic paraparesis.
Abstract: Familial Alzheimer's disease due to presenilin 1 (PSEN1) mutations shows considerable phenotypic variability with differences in neuropathology and neurological symptoms. Spastic paraparesis is a common neurological phenotype associated with Alzheimer's disease arising from PSEN1 mutations. To investigate whether known genes that cause spastic paraparesis could act as Alzheimer's disease-modifier genes, we sequenced nine spastic paraparesis genes in three Alzheimer's disease families with PSEN1 exon 9 deletions. We did not observe any correlation of polymorphisms or mutations in the nine spastic paraparesis genes with the variable phenotype seen in families with Alzheimer's disease and spastic paraparesis. These results suggest a need for a continuing search for genes that cause the phenotypic variation in Alzheimer's disease and spastic paraparesis.
3 citations