Lower limb or circumferential flaccidity is a symptom of the aqueous salt metabolism disorder type of Barth syndrome. The primary etiology of the disease is inconclusive. Most scholars believe that it is an autosomal recessive disorder. So what are the possible causes of lower limb or peripheral flaccid paralysis? The following is an explanation of the causes: Pathogenesis The cause of this disease is still inconclusive. Most scholars believe that it is an autosomal recessive disorder. There have been reports of 5 out of 9 siblings in a family and 4 cases in 2 consecutive generations. Modern molecular biology techniques have also revealed that Bartter syndrome is caused by mutations in the ion transporter protein gene on renal tubular epithelial cells. More than 20 mutations have been identified in the Na-K-2Cl- gene, located at 15q12-21, with 16 exons and encoding 1099 amino acids, for the Na-K-2Cl- channel in infantile Batter syndrome. Classic Bartter syndrome is caused by mutations in the CICNKB gene, located at 1q38, which encodes a basolateral Cl-channel containing 687 amino acids, and about 20 mutation types have been identified. Adult Bartter syndrome, also known as Batter-Gietlman syndrome, is caused by mutations in the thiazide-sensitive Na-K channel gene (SCI12A3), which is located at 16q913 and encodes 1,021 amino acids, and up to 40 mutations have been identified. In addition, mutations in the potassium channel gene (ROWK) have been found in some patients. Thus, Batter syndrome can be identified as a clinical syndrome caused by mutations in several of these ion channel genes.