Homozygous and heterozygous PINK1 mutations: Considerations for diagnosis and care of Parkinson's disease patients
ABSTRACT The first mutations described in PINK1 were homozygous. More recently, heterozygous mutations have been reported but the role of heterozygosity in disease pathogenesis is still debated. We describe two unrelated cases with PINK1 mutations (homozygous nonsense and heterozygous missense) that highlight issues regarding the role of heterozygous mutations and the utility of genetic screening in patient care.
- SourceAvailable from: Daniele Ghezzi[Show abstract] [Hide abstract]
ABSTRACT: Heterozygous rare variants in the PINK1 gene, as well as in other genes causing autosomal recessive parkinsonism, have been reported both in patients and healthy controls. Their pathogenic significance is uncertain, but they have been suggested to represent risk factors to develop Parkinson disease (PD). The few large studies that assessed the frequency of PINK1 heterozygotes in cases and controls yielded controversial results, and the phenotypic spectrum is largely unknown. We retrospectively analyzed the occurrence of PINK1 heterozygous rare variants in over 1100 sporadic and familial patients of all onset ages and in 400 controls. Twenty patients and 6 controls were heterozygous, with frequencies (1.8% vs. 1.5%) not significantly different in the two groups. Clinical features of heterozygotes were indistinguishable to those of wild-type patients, with mean disease onset 10 years later than in carriers of two mutations but worse disease progression. A meta-analysis indicated that, in PINK1 heterozygotes, the PD risk is only slightly increased with a non significant odds ratio of 1.62. These findings suggest that PINK1 heterozygous rare variants play only a minor susceptibility role in the context of a multifactorial model of PD. Hence, their significance should be kept distinct from that of homozygous/compound heterozygous mutations, that cause parkinsonism inherited in a mendelian fashion.Human Mutation 04/2008; 29(4):565. DOI:10.1002/humu.20719 · 5.05 Impact Factor
- 05/2012, Degree: PhD
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ABSTRACT: Our objective was to assess the role of defects of mitochondrial function as contributing factors in the pathogenesis and/or progression of amyotrophic lateral sclerosis (ALS); mitochondrial genome structural alterations were investigated. DNA lesions, point alterations and gross rearrangements were screened by specific applications of real-time PCR including an optimized rapid gene-specific method for the accurate quantification of mitochondrial DNA (mtDNA) lesions as well as sequencing on skeletal muscle biopsies of three patients presenting with motor neuron disease. We found a higher frequency of mtDNA lesions, including multiple deletions, particularly in the only SOD1 mutated patient as well as in a patient negative for mutations in SOD1 but presenting a severe form of the disease. The occurrence and the extent of mtDNA lesions of the cases here presented were consistent in all the examined clinical phenotypes of ALS (SOD1 related ALS, bulbar onset, spinal onset) and correlated with the severity of clinical course of the illness and with the presence of SOD1 mutation as well. In conclusion, the strong association with mtDNA damages supports the hypothesis that mitochondrial dysfunction in skeletal muscle may contribute to the pathogenesis and progression of ALS.Amyotrophic Lateral Sclerosis 10/2012; DOI:10.3109/21678421.2012.735239 · 2.37 Impact Factor