Hempelmann et al. (2006) studied an Omani family of 23 members, of which six (two males and four females) were diagnosed with paroxysmal nonkinesigenic dyskinesia (PNKD) to investigate whether this disorder mapped to the myofibrillogenesis regulator gene (MR1). Genotyping of six microsatellite markers across the MR-1 region was carried out on extracted DNA obtained from 11 family members (six patients and five unaffected) and 129 healthy Omani blood donors as controls. Two-point lod scores and parametric multipoint linkage analysis were calculated and performed with the assumption of autosomal dominant inheritance, a disease allele frequency of 0.0001 and a penetrance of 95%. The marker D2S164 was found to show a perfect co-segregation with the PNKD trait. In all 11 family members, mutation screening of the MR-1 gene by sequencing of 10 exons, the adjacent exon/intron boundaries and the 5'-regulatory region was performed. A missense mutation (c.20C>T) in a heterogeneous form at position 20 in exon 1 of the MR-1 gene, resulting in A7V change in the protein, was identified by sequence analysis in all the six patients and was absent in the unaffected family members and the controls. Another heterogeneous C to T transition in the 5'-untranslated region at nucleotide position -39 was detected in two patients and two unaffected family members and not in the control population, but this sequence variation did not co-segregate with the PNKD trait in the Omani family. No other mutation was detected in the other exons or adjacent splice junctions in any of the studied family members. Hempelmann et al. (2006) suggested that due to the geographical isolation of Omani tribes, a founder mutation of European origin could not be the cause of PNKD, and that this had probably arisen as a de novo event. Incidentally, this was the first Arab family to be described with PNKD due to mutation in the MR1 gene.