Molecular genetic studies of DMT1 on 12q in French-Canadian restless legs syndrome patients and families.
ABSTRACT Converging evidence from clinical observations, brain imaging and pathological findings strongly indicate impaired brain iron regulation in restless legs syndrome (RLS). Animal models with mutation in (DMT1) divalent metal transporter 1 gene, an important brain iron transporter, demonstrate a similar iron deficiency profile as found in RLS brain. The human DMT1 gene, mapped to chromosome 12q near the RLS1 locus, qualifies as an excellent functional and possible positional candidate for RLS. DMT1 protein levels were assessed in lymphoblastoid cell lines from RLS patients and controls. Linkage analyses were carried out with markers flanking and within the DMT1 gene. Selected patient samples from RLS families with compatible linkage to the RLS1 locus on 12q were fully sequenced in both the coding regions and the long stretches of UTR sequences. Finally, selected sequence variants were further studied in case/control and family-based association tests. A clinical association of anemia and RLS was further confirmed in this study. There was no detectable difference in DMT1 protein levels between RLS patient lymphoblastoid cell lines and normal controls. Non-parametric linkage analyses failed to identify any significant linkage signals within the DMT1 gene region. Sequencing of selected patients did not detect any sequence variant(s) compatible with DMT1 harboring RLS causative mutation(s). Further studies did not find any association between ten SNPs, spanning the whole DMT1 gene region, and RLS affection status. Finally, two DMT1 intronic SNPs showed positive association with RLS in patients with a history of anemia, when compared to RLS patients without anemia.
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ABSTRACT: Growing evidence suggests that iron accumulation in the substantia nigra (SN) is involved in the pathology of Parkinson's diseases (PD). Divalent metal transporter 1 (DMT1) is an endogenous transporter for ferrous iron, the levels of which are significantly increased in the SN in postmortem PD brains. To study the possible association of DMT1 gene with PD occurrence, one mutation (1303C/A) and two single nucleotide polymorphisms (SNPs) (1254T/C and IVS4+44C/A) in DMT1 gene were investigated in 192 PD patients in a Han Chinese population and 193 healthy controls by method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Direct sequencing was performed in 10% of the samples to validate the genotyping results. Our results failed to find any significant association between the tested genotypes, alleles or mutation and PD, however, a haplotype (C alleles of 1254T and IVS4+44C/A polymorphisms) occurred at greater frequencies in PD subjects compared with that of control (18.2% versus 11.4%, OR=1.72, 95% CI=1.15-2.59, P=0.01). These results suggest that CC haplotype in DMT1 gene is a possible risk factor for PD in this Han Chinese population.Neuroscience Letters 09/2011; 501(3):128-31. · 2.11 Impact Factor