PQBP1 and syndromic intellectual disability: Polyglutamine binding protein 1 (PQBP1), a polyglutamine tract-binding protein [4, 5], is involved in the pathology of polyglutamine diseases, such as spinocerebellar ataxia type-16 and Huntington’s disease [5], and mutations in PQBP1 cause syndromic intellectual disability (ID) with microcephaly named Renpenning’s syndrome and several other syndromes or non-syndromic IDs [7–10].