Renal tubular abnormalities in hydrops fetalis: a histological and immunohistochemical study

Renal tubular dysgenesis in an hydropic fetus with trisomy 21: a case report with literature review

Renal tubular dysgenesis (RTD) is a rare form of noncystic renal disease characterized by paucity or absence of proximal renal tubules. Always lethal in the perinatal period, it has been associated with Potter sequence and with other congenital malformations. An autosomal recessive inheritance has been suggested. We present a case of renal tubular dysgenesis associated with fetal hydrops and trisomy 21, with a review of relevant literature.

Renal tubular dysgenesis (RTD) - an important cause of the oligohydramnion-sequence. Report of 3 cases and review of the literature

Renal tubular dysgenesis (RTD) is a disorder characterized by neonatal renal failure and regular gross renal architecture, although the histological features of immature and shortened proximal tubules lead to neonatal death. The pathogenesis of this condition includes a congenital familial condition, a twin-twin transfusion syndrome, and an angiotensin-converting enzyme inhibitor intake by the mother. The clinical picture shows an association with oligohydramnia, pulmonary hypoplasia, and skull ossification defects. In the present paper, we report the occurrence of RTD in three infants of a consanguinous couple and compared our data with those of the literature. Our data confirm that late second trimester demonstration of oligohydramnion, with structurally normal kidneys and with or without skull ossification defects, allows the diagnosis of renal tubular dysgenesis, which, however, has to be confirmed by histological and immunohistological examinations of the kidney.

Renal tubular dysgenesis in twin-twin transfusion syndrome

In twin-twin transfusion syndrome (TTTS), the disparity in circulation is reflected in discordant fetal growth, urine output, and amniotic fluid accumulation. The effect of uneven shunting of the growth factor and nutrient-rich vasculature on development and differentiation of the kidney has not been well studied. We analyzed renal tubular growth and differentiation in 25 fetal autopsies with TTTS (13 donors and 12 recipients, including 9 sibling pairs) between 18 and 33 weeks gestation. Immunohistochemical markers for fumarylacetoacetate hydrolase (FAH), Leu-M1, and Lotus tetragonolobus (LTA) were used to identify proximal convoluted tubules, and epithelial membrane antigen (EMA) was used to demonstrate distal convoluted and collecting tubules. FAH appeared to be more specific and reliable than either Leu-M1 or LTA in the identification of proximal tubules. Donors tended to demonstrate a paucity of proximal tubules with crowding of glomeruli characteristic of renal tubular dysgenesis (RTD). The degree of dysgenesis was greater in later gestations and associated with more severe growth restriction. Donors in TTTS are at risk for the development of RTD. Several authors suggest ischemia as the underlying cause of "acquired" RTD. However, in this setting there is no evidence of cell death or necrosis, and we suggest that hypoperfusion leading to decreased glomerular filtration is the underlying etiology, with the severity of RTD related to the degree of shunting.

Amniotic fluid biochemistry in second-trimester trisomic pregnancies: relationships to fetal organ maturation and dysfunction

Protein and enzyme patterns were investigated in amniotic fluid samples of 12 trisomy 21 and five trisomy 18, between 11 and 16 weeks and of a control group of 50 chromosomally and anatomically normal pregnancies at the same gestational age. Positive correlations were found between gestational age and the concentration of urea (P<0.05), creatinine (P<0.01), beta2-microglobulin (P < 0.0001), hCG (P < 0.01), ALP (P < 0.001), LAP (P < 0.0001) and GGT (P <0.0005) in the amniotic fluid of euploid pregnancies. There were also significant correlations between the concentrations of the different variables measured except for hCG and AFP. Different protein and enzyme patterns were found in the amniotic fluid of aneuploid pregnancies where only beta2-microglobulin concentration was significantly correlated with advancing gestational age. The beta2-microglobulin concentration was significantly (P <0.05) higher in aneuploid fetuses presenting with hydrops compared to those without. These findings suggest that the changes in amniotic composition found during the fourth month of normal pregnancies reflect mainly the maturation of the fetal renal glomerular function and the arrival of enzymes from the digestive and respiratory tract into the amniotic cavity. In trisomy 21, there is evidence of a delay in the maturation of these organs whereas in trisomy 18, there is a reduced production of most proteins and enzymes.