NS is an autosomal dominant disorder characterized by dysmorphic facial features, proportionate short stature, and decreased bone mineral density (BMD),80,81 as well as heart disease.82,83 To circumvent the lethality of SHP2 null mutations and study SHP2’s function in the osteoblastic cell lineage, Ptpn11 floxed alleles have been created13,77 and bred with a series of Cre alleles to target osteoblastic cells at various developmental stages. The gene discussed is PTPN11; the disease is heart disorder.