BLTP1 and Hydrocephalus: As a homozygous stop-gain allele in this gene was suspected to cause a syndromic neurological disorder in a fetus (described in more details in this manuscript as fetus SA1.II.1) with cerebellar malformations, hydrocephalus, micrognathia, club feet, arthrogryposis with flexed deformity, pleural effusion, and death 1 hr after birth,13 we hypothesized that KIAA1109 variants cause an autosomal-recessive (AR) brain development disorder with arthrogryposis.