An overlap syndrome is a medical condition which shares features of at least two more widely recognised disorders.

Examples of overlap syndromes in rheumatology include mixed connective tissue disease and scleromyositis.

Diagnosis depends on which diseases the patient shows symptoms and has positive antibodies for in their lab serology.

Biologic drugs, i.e. anti-TNFα or anti-CD20 monoclonal antibodies, have been recently introduced as alternative treatments in refractory cases.

[4] In cardiology, genetic conditions such as Brugada syndrome can share features with related disorders caused by mutations in the same gene.