ALDH18A1 and microcephaly: Mutations in the aldehyde dehydrogenase 18 family member A1 (ALDH18A1) gene result in delta‐1‐pyrroline‐5‐carboxylate synthetase (P5CS) deficiency, were known to cause a condition presenting some phenotypic resemblance with SPG9, including a neurodevelopmental syndrome with microcephaly [21].