In parallel, a recent study in 9 outbred families identified mutations in spliceosome genes peptidylprolyl isomerase like 1 (PPIL1) and pre-RNA processing-17 (PRP17) causing neurodegenerative pontocerebellar hypoplasia with microcephaly, where one of the probands presented both microcephaly (-4SD) and hydrocephalus[79]. This evidence concerns the gene PPIL1 and microcephaly.