It can be from an atypical number of chromosomes or a structural abnormality in one or more chromosomes.

To be noticeable, 50% of hairs must be affected by the structural abnormality.

Recent research has identified a structural abnormality in the brains of those with narcissistic personality disorder, specifically noting less volume of gray matter in the left anterior insula.

Pericardial effusion usually results from a disturbed equilibrium between the production and re-absorption of pericardial fluid, or from a structural abnormality that allows fluid to enter the pericardial cavity.

Moderate alcohol consumption has also been shown to reduce insulin resistance, which can cause structural abnormalities in the heart.