Osteogenesis imperfecta (OI) is the most prevalent heritable bone fragility disorder in children. It has been known for three decades that the majority of individuals with OI have mutations in COL1A1 or COL1A2, the two genes coding for collagen type I alpha chains, but in the past 10 years defects in at least 17 other genes have been linked to OI. Almost all individuals with a typical OI phenotype have a mutation in one of the currently known genes. Regarding medical treatment, intravenous bisphosphonate therapy is the most widely used medical approach. This has a marked effect on vertebra in growing children and can lead to vertebral reshaping after compression fractures, but there is little effect of bisphosphonate therapy on the development of scoliosis. Bisphosphonate treatment decreases long-bone fracture rates, but such fractures are still frequent. Newer medications with anti-resorptive and bone anabolic action are being investigated in an attempt to improve on the efficacy of bisphosphonates but the safety and efficacy of these new approaches in children with OI is not yet established.

Abstract-Familial hyperaldosteronism type 1 is an autosomal dominant disorder attributed to a chimeric CYP11B1/ CYP11B2 gene (CG). Its prevalence and manifestation in the pediatric population has not been established. We aimed to investigate the prevalence of familial hyperaldosteronism type 1 in Chilean hypertensive children and to describe their clinical and biochemical characteristics. We studied 130 untreated hypertensive children (4 to 16 years old). Blood samples for measuring plasma potassium, serum aldosterone, plasma renin activity, aldosterone/renin ratio, and DNA were collected. The detection of CG was performed using long-extension PCR. We found 4 (3.08%) of 130 children with CG who belonged to 4 unrelated families. The 4 patients with CG had very high aldosterone/renin ratio (49 to 242). In addition, we found 4 children and 5 adults who were affected among 21 first-degree relatives. Of the 8 affected children, 6 presented severe hypertension, 1 presented prehypertension, and 1 presented normotension. High serum aldosterone levels (Ͼ17.7 ng/dL) were detected in 6 of 8 subjects (range: 18.6 to 48.4 ng/dL) and suppressed plasma renin activity (Յ0.5 ng/mL per hour) and high aldosterone/renin ratio (Ͼ10) in 8 of 8 children (range: 49 to 242). Hypokalemia was observed in only 1 of 8 children. We demonstrated that the prevalence of familial hyperaldosteronism type 1 in a pediatric hypertensive pediatric population was surprisingly high. We found a high variability in the clinical and biochemical characteristics of the affected patients, which suggests that familial hyperaldosteronism type 1 is a heterogeneous disease with a wide spectrum of presentations even within the same family group. (Hypertension. 2011; 57:1117-1121.) • Online Data Supplement Key Words: arterial hypertension Ⅲ aldosterone Ⅲ familial hyperaldosteronism Ⅲ glucocorticoid-remediable aldosteronism Ⅲ children F amilial hyperaldosteronism type I (FH-I; Online Mendelian Inheritance in Man, No. 103900), which is also known as glucocorticoid-remediable aldosteronism, is often characterized by severe hypertension, variable hyperaldosteronism, low plasma renin activity (PRA), normal or decreased serum potassium, and abnormal adrenal steroid production, including 18-oxocortisol and 18-hydroxycortisol, in adults. 1 FH-I occurs because of an unequal crossing over of the genes that encode the steroid 11ß-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B1) enzymes, which results in a chimeric CYP11B1/CYP11B2 gene (CG) with aldosterone synthase activity that is regulated by plasma adrenocorticotropic hormone levels instead of angiotensin II 2 ; this results in an ectopic expression of aldosterone synthase in the zone fasciculate. 3 FH-I is an autosomal dominant disorder, and different pedigrees exhibit different crossover patterns of the hybrid gene, which suggests that the mutations arose independently in each pedigree. 4 In the hypertensive adult population, this monogenic form of aldosteronism is thought to account for only 0.5% to 1.0% o...