Objective: We aimed to elucidatewhether single nucleotide polymorphisms within the XDP locus affect the phenotypic expression of XDP.

Background: X-linked Dystonia-Parkinsonism (XDP, DYT3, Lubag Disease, OMIM # 314250) exhibits variability with respect to age at onset and with symptoms that range from very mild signs to severe forms of the disease. The considerable phenotypic variability seen in XDP suggests the presence of disease modifiers, such as genetic factors influencing disease expression.

Methods: 280 genetically confirmed XDP patients were included in the study. Logistic regression analysis was done to evaluate the association between phenotypes and four SNPs of interest: ChrX:71102421C>G, rs41484056, rs41438158 and ChrX:71653235C>T. Student’s t-tests were used to compare continuous quantitative outcome measures while Z-test was used to compare proportions of patients.

Results: The ChrX:71102421C>Gpolymorphism had a significant effect on the presence of neck/shoulder dystonia (p=0.0026) while rs41484056was associated with the presence of arm dystonia (p=0.0222).Logistic regression analysis showed that none of the SNPs influence age at onset of illness. Likewise, there was also no association seen between any of the SNPs and the initial symptom (whether dystonia or parkinsonism) and the region of initial dystonic manifestation.

Conclusions: Significant association was seen betweenChrX:71102421C>G and rs41484056 and the dystonic symptoms neck/shoulder dystonia and arm dystonia, respectively. This findingmayindicate that genetic factors influence disease expression in XDPand hence, the phenotypic variability.   

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MDS Abstracts - https://www.mdsabstracts.org/abstract/association-analysis-of-single-nucleotide-polymorphisms-near-the-dyt3-locus-to-dystonic-symptoms-in-x-linked-dystonia-parkinsonism/