Mutations of MSX1 are observed in the Pierre- Robin sequence, which may be one of the features of congenital defects or is observed as an isolated defect.
Frequencies of rare alleles at the MSX1 locus are significantly higher among 34 infants with limb deficiency compared to 482 infants with other isolated birth defects (oral clefts, dislocation of hip, clubfoot, hypospadias, polydactyly, or syndactyly) (chi2 = 11.0, df = 3, P = 0.012).