Mirror movements are involuntary movements of one side of the body that mirror intentional movements on the opposite side [1]. Affected subjects have a disorganized motor system and are unable to perform purely unimanual movements or skilled dissociated movements of the two hands [2, 3]. Isolated congenital mirror movements (CMM) constitute a rare disorder characterized by mirror movements that persist throughout adulthood, without any additional manifestation. Research on CMM is a fast moving field which has recently gained attention with several breakthroughs in the past few years [2–6]. After DCC and RAD51, implicated in both autosomal dominant

CMM and simplex cases [4–6], homozygous mutations in the dynein axonemal light chain 4 gene (DNAL4) were recently reported in a single family with congenital mirror movements (CMM)[7]. DNAL4 is potentially responsible for an autosomal recessive form of the disease, which might suggest its implication in some simplex cases. However, Sanger sequencing of DNAL4 in 2 familial (albeit with autosomal dominant inheritance) and 11 simplex cases did not identify any mutation [7]. These 13 index cases had previously been screened for DCC and RAD51 abnormalities.