Parkin mutations in familial and sporadic Parkinson's disease among Indians

Department of Genetics, University of Delhi, South Campus, Benito Juarez Road, New Delhi 110021, India.
Parkinsonism & Related Disorders (Impact Factor: 3.97). 06/2006; 12(4):239-45. DOI: 10.1016/j.parkreldis.2005.12.004
Source: PubMed


We observed a mutation frequency of 8.5% in Parkin gene among Indian PD patients based on sequencing and gene dosage analysis of its exons. We identified nine point mutations of which seven are novel and hitherto unreported. These mutations accounted for 14.3% familial PD, 6.9% young onset and 5.9% late onset sporadic PD. Of the 20 PD patients with mutations only two had homozygous mutations and one was a compound heterozygote. Homozygous exonic deletions were absent but heterozygous exon rearrangements were observed in 9.2% of patients (19% familial PD and 4.5% young onset sporadic PD).

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    • "Parkin gene encodes for Parkin protein (subunit of E3 ubiquitin ligase) involved in the proteosomal degradation. Chaudhary et al.[28] analyzed the Parkin mutations in familial and sporadic Parkinson’s disease among Indians. They found that mutation frequency of 8.5% in the Parkin gene among Indian PD patients. "
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    • "Multiple sequence alignment and estimation of the tolerability of the observed parkin substitutions indicated that they were probably tolerable (Figure 2a). The reported frequency of parkin associated parkinsonism was similarly low in populations of India where the Gln34Arg substitution was previously observed [52,53]. "
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    ABSTRACT: Parkinson's disease is a progressive neurodegenerative disorder, where most cases are sporadic with a late onset. In rare incidences familial forms of early-onset parkinsonism occur, and when recessively inherited, cases are often explained by mutations in either the parkin (PARK2) or PINK1 (PARK6) gene or on exceptional occasions the DJ-1 (PARK7) or ATP13A2 (PARK9) gene. Recessively inherited deletions/duplications and point mutations in the parkin gene are the most common cause of early-onset parkinsonism known so far, but in an increasing number of studies, genetic variations in the serine/threonine kinase domain of the PINK1 gene are found to explain early-onset parkinsonism. In this study all families were from a population with a high incidence of consanguinity. We investigated 11 consanguineous families comprising 17 affected with recessively inherited young-onset parkinsonism for mutations both in the parkin and PINK1 gene. Exons and flanking regions were sequenced, and segregation patterns of genetic variation were assessed in members of the respective families. An exon dosage analysis was performed for all exons in both genes. In the parkin gene, a three generation family was identified with an exon 4 deletion segregating with disease. Both affected were homozygous for the deletion that segregated on a haplotype that spanned the gene in a haplotype segregation analysis that was performed using additional markers. Exon dosage analysis confirmed the recessive pattern of inheritance with heterozygous deletions segregating in healthy family members. In the PINK1 gene we identified two novel putative pathogenic substitutions, P416R and S419P, located in a conserved motif of the serine/threonine kinase domain. Both substitutions segregated with disease in agreement with a recessive pattern of inheritance within respective families and both were present as homozygous in two affected each. We also discuss common polymorphisms in the two genes found to be co-segregating within families. Our results further extend on the involvement of PINK1 mutations in recessive early-onset parkinsonism with clinical features similar to carriers of parkin mutations.
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