Thus, the role of SMAD3 in a wide phenotypic spectrum with different types of variants prompted us to review all the individuals with a SMAD3 (likely) pathogenic variant from our Centre and to compare them with published cases, first to determine an estimated frequency of the main clinical signs in SRD and the presence of any genotype‐phenotype correlation associated with variants of this gene. The gene discussed is SMAD3; the disease is dopa-responsive dystonia due to sepiapterin reductase deficiency.