NDNF and cartilage-hair hypoplasia: As a result, the study identified three unrelated CHH probands with heterozygous protein truncating mutations in NDNF (NM_024574.3: c.184A>T, p.K62∗; c.381del, p.Y128Tfs∗55; c.1406G>A, p.W469∗) and an additional heterozygous missense variant (NM_024574.3: c.602C>G, p.T201S).