GCH1 and cerebellar ataxia: Genetic testing for spinocerebellar ataxias, Huntington disease–like syndromes, and hereditary parkinsonism uncovered no extended trinucleotide repeat in ATXN1-3, CACNA1A, TBP, and FMR1; no pathogenic variants in PRKN and GCH1; and no hotspot variant in LRRK2(G2019S) or common point variants and copy number variations in DJ1, PINK1, UCHL1, SNCA, and ATP13A2. Further, no pathogenic variants were found in NPC1, NPC2, or NOTCH3. Patient 1 was not formally assessed by specialists in child psychiatry during childhood/adolescence.