Adrenal aldosterone-producing adenomas (APAs) constitutively produce the salt-retaining hormone aldosterone and are a common cause of severe hypertension. Recurrent mutations in the potassium channel KCNJ5 that result in cell depolarization and Ca2+ influx cause ~40% of these tumors1. We found five somatic mutations (four altering glycine 403, one altering isoleucine 770) in CACNA1D, encoding a voltage-gated calcium channel, among 43 non-KCNJ5-mutant APAs. These mutations lie in S6 segments that line the channel pore. Both result in channel activation at less depolarized potentials, and glycine 403 mutations also impair channel inactivation. These effects are inferred to cause increased Ca2+ influx, the sufficient stimulus for aldosterone production and cell proliferation in adrenal glomerulosa2. Remarkably, we identified de novo mutations at the identical positions in two children with a previously undescribed syndrome featuring primary aldosteronism and neuromuscular abnormalities. These findings implicate gain of function Ca2+ channel mutations in aldosterone-producing adenomas and primary aldosteronism.

Osteogenesis imperfecta (OI) is a heritable disorder ofconnective tissue associated with fractures, osteopenia, and short stature. 01 results from mutations affecting the proal or proa2 gene of type I collagen. We describe a strain of mice with a nonlethal recessively inherited mutation (oim) that results in phenotypic and biochemical features that simulate moderate to severe human 01. Although imperfect osteogenesis has been previously observed in bovine, feline, and murine species, none of these have duplicated both the biochemical and clinical findings associated with human OI (4-7). The Mov-13 mouse, which has a transcriptional block of the proal(I) collagen gene, has provided a potential model of human 01 type II (8-13). More recently, several transgenic variants of Mov-13 and normal mice have been created as useful models of mild 01 type I or lethal OI type II (tt, 14, 15).In this report we describe a naturally occurring mouse mutation that produces phenotypic and biochemical features similar to those seen in moderate to severe human OI. We have named this mutation osteogenesis imperfecta murine (oim). Homozygous oim mice have osteopenia, fractures, and progressive skeletal deformities. Our data indicate that these mice are deficient in proa2(I) collagen because of a G deletion at nucleotide 3983 of the Cola-2 gene. This mutation results in tissue accumulation of al(I) homotrimeric collagen in the extracellular matrix. Homozygous oim mice should permit the study of type I collagen pathophysiology in a manner not possible in humans. MATERIALS AND METHODSRadiographic and Microscopic Examination. Whole-body radiographs were taken in a Faxitron x-ray machine (34 keV for 1.5 min) using Kodak OM1 film. For light microscopy, excised femurs were fixed in neutral buffered Formalin for 24 hr, decalcified in 10% (wt/vol) EDTA in 0.1 M Tris'HCl buffer, pH 6.9, for 14 days at 4°C, embedded in paraffin, sectioned, and stained with hematoxylin and eosin.Isolation and Culture of Dermal Fibroblasts. Dermis was obtained from the back of 3-to 5-day-old homozygous oim and wild-type pups. The skin was rinsed with iodine then 70o (vol/vol) ethanol, excised, and minced to 1-to 3-mm2 pieces.Explants were grown for 2 weeks in Dulbecco's modified Eagle's medium supplemented with 10%o fetal bovine serum, streptomycin at 100 jug/ml, penicillin at 100 units/ml, and amphotericin B at 0.25 jig/ml. Cultures were assayed in the second passage.Collagen and Procollagen Analysis in Vitro. Fibroblast cultures were grown several days past visual confluence in 10-cm2 dishes. The medium was then supplemented with 150 ,uM sodium ascorbate and 24 hr later the cultures were incubated for 30 min in Dulbecco's modified Eagle's medium plus 1% dialyzed fetal bovine serum, antibiotics, 100 ,uM each nonessential amino acids but no proline, and 150 ,uM sodium ascorbate (starve medium). De novo synthesized proteins were radiolabeled for 2 hr (short-label analysis) or 24 hr (steady-state analysis) with starve medium containing 20 ,uCi (1 Ci = 37 ...

The combination of exercise plus an antiresoptive drug may be useful for protecting bone health during long-duration spaceflight.

Osteogenesis imperfecta (OI) is the most common of the inherited connective tissue disorders that primarily affect bone. However, it is a systemic disorder, as evidenced by the occurrence of ocular complications, dentinogenesis imperfecta, hearing loss, joint laxity, restrictive pulmonary disease, and short stature. The OI classification initially included four phenotypes (I-IV) involving COL1A1 and COL1A2 mutations. Three new phenotypes have been added, of which one, type VII, is the result of mutations of the cartilage-associated protein (CRTAP) gene. Investigation of recessive forms of OI particularly reported among South African blacks have revealed mutations involving both the CRTAP gene and the leucine proline-enriched proteoglycan 1 (LEPRE1) gene, each involved in collagen proline-3 hydroxylation. Issues related to the treatment of OI with bisphosphonates involve patient selection, evaluation of the results of treatment, and the duration of treatment. Also, questions exist regarding the difference in treatment response between children and adults with OI. Other treatment options, such as recombinant human parathyroid hormone (1-34), Rank ligand inhibitors, and stem cell technology, are being evaluated or are of future investigative interest.