| ObjectivesIn this study,We collected six Chinese PKD pedigrees with no other paroxysmal diseases such as epilepsy,migraine,or infantile convulsion. The aim of the study is to deeply research the clinical characteristics of Chinese PKD pedigrees and search for paroxysmal kinesigenic dyskinesia susceptibility gene(s) using a Chinese multiplex family of Pure PKD.Methods1) Clinical research:we contrasted the onset age and severity of these 6 pedigrees and another 12 reported by others in China with that of 60 PKD pedigrees in other countries on clinical and statistical analysis by using a simple generalized paired t-test and a Wilcoxon signed rank test.2) Gene mapping:After excluding the linkage related to chromosome 16 which contains the two known gene loci of PKD(EKD1 and EKD2),two genome-wide screens were performed,using ABI Linkage Mapping Set v.2.5-MD10 and Illumina Infinium Human Linkage-12 panel,in a Chinese multiplex family of Pure PKD with genetic anticipation.Linkage,Merlin and Genehunter-Two-Locus software were used to perform parametric and nonparametric linkage analyses under the modes of single-trait-locus and two-trait-locus linkage analysis.3) Candidate genes cloning:we performed a bioinformational inquiry of all known genes in both loci interval and selected 4 genes(KCNG3,SLC8A1,PRKCE and FGF12) as candidate genes for mutation analysis by polymerase chain reaction(PCR) and DNA direct sequencing.Results1) Clinically,pure PKD families in China showed the phenomenon of progressively earlier and more severe as it is passed on to the next generation.Statistically,the mean difference of disease onset in pure PKD in China group was 5.2 years in both statistical analysis(p＜0.0001) but no statistical significance(P＞0.01) between parent and offspring generation in complicated PKD.2) The STR result identified a suspective locus on chromosome 3q27-q29 with a maximum two-point LOD score of 1.85 at 0=0 and the maximum muliti-point NPL score of 4.64(P=0.004) on D3S1580.Fine mapping showed a maximum two-Lod score of 2.82 atθ=0 on D3S3669. The new pure PKD locus lies with an 10.2cM interval on 3q28-29, between D3S1314 and D3S1265.The SNP data demonstrated two loci with suggestive linkage:one is mapped to a 7.18 cM region on chromosome 2p21-22 between rs1509562 and rs1016607(LOD score of 2.35;NPL score of 5.30;P less than.00001);the other is mapped to the a 13.78 cM region on chromosome 3q28-29 between rs10937369 and rs711995(LOD score of 2.39;NPL score of 5.74;P less than.00001).In addition,an interaction was suggested with joint analyses of these two loci,which gave rise to a 2-locus LOD score of 3.81 under the assumption of a multiplicative model and a 2-locus NPL score of 7.81(P =0.0006).3) The mutation analysis result showed that only eight common single nucleotide polymorphisms(SNPs) were detected and they were not the causative variants. Conclusions1) Paroxysmal kinesigenic dyskinesia would be divided into pure and complicated subtype.2) This study provides genetic evidences of two novel loci for Pure PKD with anticipation and suggests that pure PKD is a new clinical subtype of PKD.3) Four candidate genes(KCNG3,SLC8A1,PRKCE and FGF12) were ruled out as the causative gene for pure PKD.
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