If a delay is noted, it is important to document whether a skill was acquired then lost. The loss of ability may be associated with a number of inborn errors of metabolism or adult onset neurodegenerative disorders. Syndrome describes a group of major and minor abnormalities that are associated frequently enough to be clinically recognizable as a specific entity. When attempting to understand the relationship between a diverse set of major and minor abnormalities, it often helps to consider the underlying developmental pathology. These include malformation, deformation and disruption.
Malformation refers to a primary defect in the cells or tissue forming an organ or organ system.
The defect may be caused by an abnormality in a gene, a group of genes, or a chromosome. Deformation refers to intrinsic or extrinsic biomechanical forces acting on the fetus to cause a structural abnormality. These are usually benign and, with the constraints removed, can be corrected. Realize that a primary malformation can lead to a secondary deformation. The risk of recurrence will depend upon the initiating event.