Renal tubular dysgenesis, a not uncommon autosomal recessive disorder leading to oligohydramnios: Role of the Renin-Angiotensin system.

Renal tubular dysgenesis is a clinical disorder that is observed in fetuses and characterized by the absence or poor development of proximal tubules, early onset and persistent oligohydramnios that leads to the Potter sequence, and skull ossification defects. It may be acquired during fetal development or inherited as an autosomal recessive disease. It was shown recently that autosomal recessive renal tubular dysgenesis is genetically heterogeneous and linked to mutations in the genes that encode components of the renin-angiotensin system. This study analyzed the clinical expression of the disease in 29 fetus/neonates from 18 unrelated families and evaluated changes in renal morphology and expression of the renin-angiotensin system. The disease was uniformly severe, with perinatal death in all cases as a result of persistent anuria and hypoxia related to pulmonary hypoplasia. Severe defects in proximal tubules were observed in all fetuses from 18 gestational weeks onward, and lesions also involved other tubular segments. They were associated with thickening of the renal arterial vasculature, from the arcuate to the afferent arteries. Renal renin expression was strikingly increased in 19 of 24 patients studied, from 13 families, whereas no renal renin was detected in four patients from three families. Angiotensinogen and angiotensin-converting enzyme were absent or present in only small amounts in the proximal tubule, in correlation with the severity of tubular abnormalities. No specific changes were detected in angiotensin II receptor expression. The severity and the early onset of the clinical and pathologic expression of the disease underline the major importance of this system in fetal kidney function and development in humans. The identification of the disease on the basis of precise histologic analysis and the research of the genetic defect now allow genetic counseling and early prenatal diagnosis.

Foetal kidney maldevelopment in maternal use of angiotensin II type I receptor antagonists.

We report renal lesions observed in a foetus exposed throughout pregnancy to angiotensin II type I (AT 1) receptor antagonists. The mother suffered from essential hypertension and was treated with Cozaar (losartan 50 mg). Autopsy examination of the foetus revealed severe renal lesions, including tubular dysgenesis, hypertrophy of the endothelial and medial cells lining the arterial and arteriolar walls, hyperplasia of the juxtaglomerular apparatus and poorly developed vasa recta. Similar lesions have already been observed in foetuses of women treated with angiotensin-converting enzyme antagonists and also in foetuses and neonates of animals undergoing experimental blockade of the renin-angiotensin system. The purpose of this report is to describe structural lesions observed in the kidneys, and, particularly, vascular lesions. Our results suggest that the use of AT 1 receptor antagonists during pregnancy may have a severe deleterious effect on kidney development in the foetus.

Isolated non-compaction of the myocardium diagnosed in the fetus: two sporadic and two familial cases.

Isolated non-compaction of the ventricular myocardium is characterized by numerous and prominent trabeculations and deep intertrabecular recesses. This rare disease is due to an arrest of myocardial morphogenesis. Most cases, when seen in children, are associated with obstructive malformations. Isolated non-compaction is even rarer in childhood, and affects predominantly the myocardium of the left ventricle. Morbidity and mortality resulting from cardiovascular complications is high. In most cases, transplantation is the final option. To our knowledge, this rare cardiac malformation has yet to be diagnosed in the fetus. We report here two sporadic cases, one male and one female, and 2 familial cases, both male, which were diagnosed prenatally and followed by fetal echocardiography. Our study indicates that isolated non-compaction is a primary disorder of early fetal development. Our cross-sectional echocardiographic examinations revealed a fetal cardiomyopathy, with prominent and numerous trabeculations and deep intertrabecular recesses of the myocardium at the apex of the ventricles. In contrast with postnatal experience, we found isolated non-compaction mostly in the right ventricle. Systolic dysfunction was found in all cases. The diagnosis was confirmed by histology in 3 fetuses dying with cardiac failure, and by postnatal cross-sectional echocardiography in the fetus who survived. Two male fetuses belonged to a family in which 3 individuals were subsequently found to be affected. We discuss the issues of prenatal diagnosis, natural history, and myocardial histology.