ABSTRACT
A genetic defect is the major determinant of an abnormality that is either present at birth or evolves over time. Various anomalies may also result from injury to the formed embryo. Many of these conditions affect the musculoskeletal system, producing cartilage and bone dysplasia, malformations or structural defects of connective tissue. In some, a specific metabolic abnormality has been identified. The single gene disorders have characteristic patterns of inheritance, which may be autosomal or X-linked, and dominant or recessive. All types of genetic disease are more likely to occur in the children of consanguineous marriages or in closed communities where many people are related to each other. All the skeletal dysplasias affect growth, although this may not be obvious at birth. Individuals who reach adulthood, though recognizably abnormal, may lead active lives, marry and have children of their own. Nevertheless, they often seek medical advice for several reasons.
