Apparent Mineralocorticoid Excess Syndrome Natural History Clinical Protocol

AME is a rare genetic disorder that is caused by a mutated HSD11B2 gene, which encodes the metabolic enzyme 11BHSD2. The altered gene interferes with the ability of 11BHSD2 to inactivate the hormone cortisol. Above-normal cortisol activity then leads to a rise in blood pressure and a reduction of potassium in the blood. It also leads to low levels of the enzyme renin and the hormone aldosterone, both of which are involved in the regulation of long-term blood pressure. Long-term high blood pressure and metabolic defects start at an early age in children with severe AME. In others, AME may start later in life and cause less serious side effects. Symptoms can include poor growth in childhood, delayed puberty, muscle weakness, heart rate irregularity, frequent urination, and thirst. If left untreated, AME can cause serious damage to the eyes, kidneys, heart, and other organs.

Current treatment with the synthetic steroid spironolactone usually improves symptoms; however, despite treatment, some individuals with AME still experience disease progression and even death within years of being diagnosed with AME. Understanding more about AME, how it progresses, and how it affects people differently may help to improve treatment options. The purpose of this study is to examine the genetic basis, natural history, disease progression, and outcome of children and adults with AME. The study will also examine the family members of study participants with AME for any genetic abnormalities and possible mild forms of AME.

This study will last 2 to 7 years. Participants and their family members will attend yearly study visits that will include interviews about medical history, symptoms, and hospital stays; a physical exam; blood pressure testing; and blood and urine collection. Interim reviews of medical records will occur as necessary. Children will undergo an x-ray of the left hand. During the initial study visit, participants will be asked questions about family members and birth size.