One defined genetic cause for hereditary lymphedema is GATA2 deficiency. This deficiency is a grouping of several disorders caused by common defect, viz., familial or sporadic inactivating mutations in one of the two parental "GATA2" genes. These autosomal dominant mutations cause a reduction, i.e. a haploinsufficiency, in the cellular levels of the gene's product, GATA2. The GATA2 protein is a transcription factor critical for the embryonic development, maintenance, and functionality of blood-forming, lympathic-forming, and other tissue-forming stem cells. In consequence of these mutations, cellular levels of GATA2 are deficient and individuals develop over time hematological, immunological, lymphatic, and/or other disorders. GATA2 deficiency-induced defects in the lymphatic vessels and valves underlies the development of lymphedema which is primarily located in the lower extremities but may also occur in other places such as the face or testes (i.e. hydrocele). This form of the deficiency, when coupled with sensorineural hearing loss which may also be due to faulty development of the lymphatic system, is sometimes termed the Emberger syndrome.