With the advent of next-generation sequencing technologies, we revisited a Sephardic Jewish kindred exhibiting AR isolated dystonia that had previously been classified as “DYT2-like.”10 The three affected siblings (now aged 61, 57, and 51 years) were the product of a consanguineous marriage between two first cousins. Both parents were neurologically normal, and there was no report of any dystonia within the wider kindred (Figure 1A and extended pedigree in Khan et al.10). In brief, in their first decade of life, all three affected siblings developed dystonia, which gradually generalized over time but remained most marked in the upper limbs and cervical and cranial regions. Initially, the siblings were reported to have an atypical form of metachromatic leukodystrophy (MLD) on the basis of markedly reduced levels of arylsulfatase A in fibroblasts and leucocytes, reduced nerve conduction velocities, and the detection of brown metachromatic granules in sural nerve biopsies. Subsequent mutational screening by Sanger sequencing demonstrated that the mother and the three siblings were homozygous and that the father was heterozygous for two variants in a cis configuration, c.[1055A>G; ∗96A>G] (RefSeq accession number NM_000487.5), which are commonly referred to collectively as the “polyA mutation,” in the gene ARSA (MIM 607574). The polyA mutation results in reduced amounts of arylsulfatase A on biochemical assay and has no clinical symptoms (a state termed pseudodeficiency). No other mutations were detected in the remainder of the gene at that time or in the current study. In this context, the detection of metachromatic granules in the sural nerve biopsy is unusual. Nonetheless, despite prolonged follow-up, no clinical or radiological features of progressive central or peripheral demyelination have developed, making MLD highly unlikely. On current examination, there are no other neurological features besides the dystonia detectable on clinical examination, and exhaustive radiological and biochemical investigations have failed to reveal any underlying cause. Extensive genetic testing—including but not confined to TOR1A, THAP1, GNAL, and ANO3—has not revealed a causal mutation in these genes. Although the severity of the dystonia has gradually increased over time, the clinical course appears relatively benign: all three of the affected siblings continue to function well in daily life, there is no significant limitation of ambulation, and fixed deformities have not developed. This study was approved by the relevant local ethics committee at our institution, and informed consent was provided by all participants in accordance with its guidelines.