Clinical application of molecular genetics in lymphatic malformations

OBJECTIVES: To describe the clinical presentation of lymphatic malformations (LM) and genotypically associated disorders and to summarize the recent literature regarding the genetic etiology of LM and provide a biologic correlation to medical and surgical management. RESULTS: LM are congenital lesions derived from a developmental abnormality of the lymphatic vessels. The severity of disease varies widely and complications can occur with higher staged disease and those associated with a known constellation of symptoms. Somatic mutations of the PIK3CA gene have been found to be an etiologic factor in the development of LM and associated overgrowth syndromes. Sirolimus is a mammalian target of rapamycin (mTOR) inhibitor that inhibits the pathway downstream of PIK3CA. Preliminary studies in select groups of patients suggest that sirolimus has a role in the medical management of certain aspects of this disease. CONCLUSIONS: Discovery of LM molecular genetics has led to the possibility of targeted therapies and highlights the importance of precision medicine in rare diseases. Identifying genetic mutations in larger cohorts of patients with LM will lead to additional insights. Knowledge of the genetic basis for disease can then lead to discovery of directed medical therapy. A specific molecular diagnosis can also help families understand better why their child is different and provide accurate counseling for subsequent pregnancies. LEVEL OF EVIDENCE: 6