Changes in skeletal dysplasia nosology.

Skeletal dysplasia (SD), also called osteochondrodysplasia (OCD), is a large group of skeletal disorders (over 400 distinct entities) caused by abnormalities in bone development and growth. SDs varies according to different natural histories, prognoses, hereditary patterns to etiopathogenetic mechanisms. At birth, the incidence is low, reported at the level of each entity, but taken collectively; the incidence is estimated at 1:5000 births. Nosology is a branch of medical science. It deals with the systematic classification of diseases and disorders. Thus, combining information about the catalogue of clinically distinct disorders, pending molecular explanations, and genotype-phenotype correlations, the classification of SDs will be more accurate. This is extremely useful for diagnosing patients with genetic skeletal diseases, especially given the expected flow of information with new sequencing technologies. Over the years, various terms and classifications of SD have been used and have attempted to order and classify this group of genetic diseases according to clinical, radiological, and molecular criteria. In 2019, the Nosology Committee of the International Skeletal Dysplasia Society (ISDS) updated the classification of SD. This new classification divides SD into 42 large groups that include 461 entities. Advances in next-generation sequencing techniques have revolutionized the entire field of genetics, with 437 different genes are currently identified in 426 (92.4%) of SDs. Nosology is a real help for the clinician in establishing a diagnosis as accurately as possible, for the recognition of new diseases while serving as a guide for the interpretation of new genetic variants.