First described by Hennekam in 1988, it is an extremely rare autosomal recessive disorder, characterized by mental retardation associated with gastro-intestinal lymphangectasia, cranial-facial anomalies (hypertelorism, etc.), and lymphedema of the lower limbs and external genitalia. In some cases, also ear and foot anomalies (talipes equinus) have been described. It is one of several syndromes involving the lymphatic system.

It is a flavanone, a direct precursor of diosmin (see), prolonging and strengthening its pharmacological activity. Further, it has strong anti-inflammatory effects.