DNAH1 and primary ciliary dyskinesia: However in some cases, it still remains difficult to have a clear-cut answer, as illustrated for DNAH1, which deletion induces a PCD and male infertility phenotype in the mouse [14] while truncating mutations in humans undoubtedly cause a MMAF phenotype (8% frequency) and only a unique rare missense mutation was so far reported to segregate with a PCD phenotype in humans [42].