In 2 unrelated patients, Ulick et al. (1979) described a disorder in the peripheral metabolism of cortisol, manifested by hypertension, hypokalemia, low plasma renin activity, and responsiveness to spironolactone. Aldosterone levels were subnormal. Although the features suggested primary mineralocorticoid excess, no overproduction of mineralocorticoid could be demonstrated. One of the patients, who had been reported by New et al. (1977), was a 3-year-old Zuni Indian girl with hypertension, hypokalemia, and decreased secretion of all known sodium-retaining corticosteroids. The second patient was a boy of Middle Eastern parentage who had a stroke with residual left hemiparesis at age 7, and was first found to be hypertensive at age 9 (blood pressure as high as 250/180 mm Hg). Other findings included growth retardation, grade III retinopathy, hypokalemia, and hyposthenuria. Biochemical studies indicated a decreased rate of conversion of active cortisol to cortisone, and the authors postulated a defect in 11-beta-hydroxy oxidation of cortisol. Ulick et al. (1979) suggested the term 'apparent mineralocorticoid excess.'
In an infant with a D-bifunctional protein deficiency ( 261515 ), van Grunsven et al. (1998) identified a 46G-A transition in the HSD17B4 gene, resulting in a gly16-to-ser (G16S) substitution within an important loop of the Rossman fold forming the NAD(+)-binding site. Biochemical analysis showed that the 3-hydroxyacyl-CoA dehydrogenase activity of the D-bifunctional protein was completely inactive, whereas the enoyl-CoA hydratase component was active. Their findings showed that the D-bifunctional protein plays an essential role in the peroxisomal beta-oxidation pathway that cannot be compensated for by the L-specific bifunctional protein. Both parents were heterozygous for the mutation.