Parkinson's disease (PD; OMIM #168600) is the second most common neurodegenerative disorder in the Western world and presents as a progressive movement disorder. The hallmark pathological features of PD are loss of dopaminergic neurons from the substantia nigra and neuronal intracellular Lewy body inclusions. Parkinsonism is typically sporadic in nature; however, several rare familial forms are linked to genetic loci, and the identification of causal mutations has provided insight into the disease process. PARK8, identified in 2002 by Funayama and colleagues, appears to be a common cause of familial PD. We describe here the cloning of a novel gene that contains missense mutations segregating with PARK8-linked PD in five families from England and Spain. Because of the tremor observed in PD and because a number of the families are of Basque descent, we have named this protein dardarin, derived from the Basque word dardara, meaning tremor.

Huntington disease is caused by the expansion of a CAG repeat encoding an extended glutamine tract in a protein called huntingtin. Although the mutant protein is widely expressed, the earliest and most striking neuropathological changes are observed in the striatum. Here we show dramatic mutation length increases (gains of up to 1000 CAG repeats) in human striatal cells early in the disease course, most likely before the onset of pathological cell loss. Studies of knock-in HD mouse models indicate that the size of the initial CAG repeat mutation may influence both onset and tissue-specific patterns of age-dependent, expansion-biased mutation length variability. Given that CAG repeat length strongly correlates with clinical severity, we suggest that somatic increases of mutation length may play a major role in the progressive nature and cell-selective aspects of both adult-onset and juvenile-onset HD pathogenesis and we discuss the implications of this interpretation of the data presented.

Risk for ischemic stroke is mediated by both environmental and genetic factors. Although several environmental exposures have been implicated, relatively little is known about the genetic basis of predisposition to this disease. Recent studies in Iceland identified risk polymorphisms in two putative candidate genes for ischemic stroke: phosphodiesterase 4D (PDE4D) and 5-lipoxygenase activating protein (ALOX5AP). A collection of North American sibling pairs concordant for ischemic stroke and two cohorts of prospectively ascertained North American ischemic stroke cases and control subjects were used for evaluation of PDE4D and ALOX5AP. Although no evidence supported linkage of ischemic stroke with either of the two candidate genes, single-nucleotide polymorphisms and haplotypic associations were observed between PDE4D and ischemic stroke. There was no evidence of association between variants of ALOX5AP and ischemic stroke. These data suggest that common variants in PDE4D may contribute to the genetic risk for ischemic stroke in multiple populations.Stroke is a leading cause of death in the Western hemisphere, 1 and 85 to 90% of strokes are ischemic. 2,3 Risk for ischemic stroke is mediated by both genetic and environmental factors. 4 A genome-wide scan was performed on an Icelandic genealogy consisting of 476 patients (clustered into 179 families) and 438 relatives in a search for stroke susceptibility genes. 5 Significant evidence for linkage with stroke was found in a 20cM region of human chromosome 5q12 (STRK1). This region included the 5′ end of a candidate gene, PDE4D. The PDE4D

We have recently identified mutations in a gene leucine-rich repeat kinase-2 (LRRK2), which cause autosomal dominant Parkinson's disease. Here, we describe two families with autosomal dominant Parkinson's disease caused by a LRRK2 G2019S mutation. We present here a clinical description of patients, including 6-(18)F-fluoro-L-dopa positron emission tomography and discuss the potential implications of this mutation, which alters a conserved residue in a domain required for kinase activation.