Distal hereditary motor neuropathies comprise a clinically and genetically heterogeneous group of disorders. We recently mapped an X-linked form of this condition to chromosome Xq13.1-q21 in two large unrelated families. The region of genetic linkage included ATP7A, which encodes a copper-transporting P-type ATPase mutated in patients with Menkes disease, a severe infantile-onset neurodegenerative condition. We identified two unique ATP7A missense mutations (p.P1386S and p.T994I) in males with distal motor neuropathy in two families. These molecular alterations impact highly conserved amino acids in the carboxyl half of ATP7A and do not directly involve the copper transporter's known critical functional domains. Studies of p.P1386S revealed normal ATP7A mRNA and protein levels, a defect in ATP7A trafficking, and partial rescue of a S. cerevisiae copper transport knockout. Although ATP7A mutations are typically associated with severe Menkes disease or its milder allelic variant, occipital horn syndrome, we demonstrate here that certain missense mutations at this locus can cause a syndrome restricted to progressive distal motor neuropathy without overt signs of systemic copper deficiency. This previously unrecognized genotype-phenotype correlation suggests an important role of the ATP7A copper transporter in motor-neuron maintenance and function.

Abstract-Primary hyperaldosteronism, one cause of which is aldosterone-producing adenomas (APAs), may account for Յ5% to 10% of cases of essential hypertension. Germline mutations have been identified in 2 rare familial forms of primary hyperaldosteronism, but it has been reported recently that somatic mutations of the KCNJ5 gene, which encodes a potassium channel, are present in some sporadic nonsyndromic APAs. To address this further we screened 2 large collections of sporadic APAs from the United Kingdom and Australia (totalling 73) and found somatic mutations in the selectivity filter of KCNJ5 in 41% (95% CI: 31% to 53%) of the APAs (30 of 73). These included the previously noted nonsynonymous mutations, G151R and L158R, and an unreported 3-base deletion, delI157, in the region of the selectivity filter. APAs containing a somatic KCNJ5 mutation were significantly larger than those without ( Key Words: hyperaldosteronism Ⅲ hypertension Ⅲ potassium channels Ⅲ KCNJ5 Ⅲ aldosterone-producing adenoma Ⅲ posture response P rimary hyperaldosteronism (PA) is now recognized as a common, treatable, and potentially curable form of hypertension, which may account for Յ10% of cases of socalled essential hypertension. [1][2][3] Most cases of PA are sporadic and result from 2 major types of adrenal pathology, an aldosterone-producing adenoma (APA) or bilateral adrenal hyperplasia. In recently published series, the frequency of APA varied between 28% and 50% of patients with PA. 4 Choi et al 5 recently reported somatic mutations in a potassium channel, KCNJ5 (also called GIRK4 or Kir3.4), in 8 of 20 APAs studied and a germline mutation in the same gene in all 3 affected members of a family with florid, early onset, nondexamethasone-suppressible PA associated with marked hyperplasia of zona fasciculata (ZF), suggesting a novel pathway that might activate growth of aldosteronesecreting cells. These mutations within the selectivity filter of the potassium channel reduce the normal K ϩ /Na ϩ selectivity of the channel, and the resulting depolarization of the adrenocortical cell could lead to calcium loading and growth. However, the APAs carrying KCNJ5 mutations were large (mean of 2.8 cm and all Ͼ2 cm in diameter) and might represent a subgroup with a phenotype more relevant to the giant hyperplastic adrenals seen in the family with the germline KCNJ5 mutation. 5 To address this issue we have screened a large collection of APAs (totalling 73) from geographically distinct centers (United Kingdom and Australia) to determine whether somatic mutations of KCNJ5 are present in unselected APAs regardless of size. We also