Bone dysplasias include a series of skeletal anomalies and malformations of various origins, which can be the expression of rare genetic syndromes. Hereditary / congenital bone dysplasias include approximately 500 different clinical phenotypes, and are predominantly caused by recessive genetic defects (both copies of the disease gene must be mutated for the disease to manifest).
These pathologies present a high phenotypic heterogeneity, with onset at different ages: in some cases the clinical diagnosis can be made in the prenatal phase, other forms of bone dysplasia are evident only at birth or, in some cases, they manifest themselves in the post-natal period, in childhood and adulthood.
Furthermore, congenital bone dysplasias can present in syndromic forms, in which the involvement of other organs is evident and, sometimes, the bone involvement can have incomplete penetrance, and not manifest itself in all affected individuals, or do so with varying degrees of severity. Conversely, congenital bone dysplasias are defined as isolated when the skeleton is the primary target of the gene defect.