Alpha fetoprotein in the antenatal diagnosis of the congenital nephrotic syndrome

In the congenital nephrotic syndrome (Finnish type), concentrations of alpha fetoprotein in the amniotic fluid and maternal serum are markedly elevated in the second trimester of pregancncy. Demonstration of this alteration allows early prenatal diagnosis of this fatal condition and elective termination of the pregnancy before 20 week's gestation.

Congenital nephrotic syndrome: prenatal diagnosis and genetic counselling by estimation of aminotic-fluid and maternal serum alpha-fetoprotein

Nine families in which a previous child had had congenital nephrotic syndrome (C.N.) sought genetic counselling and possible antenatal diagnosis of fetal disease. Maternal serum and amniotic-fluid alpha-fetoprotein (A.F.P.) assays were carried out between the 15th and 20th weeks of subsequent pregnancies. Seven women in whom A.F.P. concentrations were normal chose to continue pregnancy, and they were all delivered of a healthy child. Markedly raised amniotic A.F.P. concentrations were found in two cases; in one of these cases maternal serum-A.F.P. was also raised. These pregnancies were terminated, and electron microscopy of the fetal kidneys showed evidence of C.N. in the fetus--i.e., loss of foot processes and an increase in the mesangial matrix of the glomeruli. The outcomes of these at-risk pregnancies indicate that prenatal diagnosis and genetic counselling are possible in families with a history of C.N. The results also stress the importance of carefully examining fetal kidneys whenever amniotic-fluid A.F.P. concentration is raised in the absence of apparent malformations.

The use of alpha fetoprotein in prenatal diagnosis

Maternal or blood levels of alpha fetal protein are elevated in the presence of certain fetal anomalies, particularly those of the neural tube in which protein from the cerebrospinal fluid may leak into the amniotic fluid. Since this is a nonspecific elevation, other diseases are potentially screened for by this determination. Alpha fetal protein levels should be measured on any amniotic fluid samples obtained during the middle trimester of pregnancy.

Congenital nephrotic syndrome of Finnish type. Study of 75 patients

Seventy-five patients with congenital nephrotic syndrome of Finnish type were identified in Finland in the period 1965-1973, giving an incidence of 12-2/10(5). A large placenta and proteinuria from birth are the hallmarks of the disease. About one-quarter of the patients had oedema and/or abdominal distension at birth and in all cases the full nephrotic syndrome was documented before 2 months. More than half of the patients died before 6 months and none lived longer than 2 years 3 months. A slight rise in blood urea nitrogen or serum creatinine levels occurred in 14 cases, but in none of these did a frank uraemia develop before death. Infection appeared to be the immediate cause of death in 31% of the cases; in 43% no cause of death other than congenital nephrotic syndrome could be shown. Thrombi in large vessels were found in 11 out of 58 necropsies.

Chemical properties of glomerular basement membrane in congenital nephrotic syndrome

Glomerular basement membranes have been isolated from kidneys of three children presenting with a congenital nephrotic syndrome. The histology of renal tissue was characterized by an increase of the mesangial area mainly due to matrix. Immunofluorescent studies showed no positive staining. After isolation, the glomerular basement membranes contained no more cellular contaminants than normal membranes. Isolated abnormal membranes exhibited, as normal preparations, less than 1% DNA, RNA, phospholipids or glycosaminoglycans. Since the protein content of both membrane preparations was comparable, significant contamination by non-proteic material did not seem likely. Although the amino acid and carbohydrate composition of both normal and abnormal membranes was very similar, the folowing statistically significant differences were observed: diseased membranes exhibited an increased number of hydroxylysine, 3- and 4-hydroxyproline residues, and an increased content of glucosyl-galactosyl-hydroxlysine units. The data suggest that, in the congenital nephrotic syndrome, the production of disaccharide-rich glomerular basement membrane subunits is enhanced, which could interfere with the packing of the peptide chains and therefore account for the altered permeability of the membrane observed in this disease.

Glomerular basement membrane antigens in congenital and acquired nephrotic syndrome in childhood

Urinary and serum glomerular basement membrane (GBM) antigens were detected by immunodiffusion in patients with nephrotic syndrome and in healthy subjects. The excretion of urinary GBM antigens was greatest in patients with congenital nephrotic syndrome of Finnish type (CNF) and in patients with acquired, therapy-resistant nephrotic syndrome who had a variety of histologically identified glomerular lesions. One GBM antigen, indistinguishable from the urinary one, was also detected in the serum of four of these patients. Excretion of urinary GBM antigens was within normal limits, in patients with steroid-sensitive nephrotic syndrome with minimal changes in renal histology and in the parents (heterozygotes) of CNF patients.

Immunological studies in congenital nephrosis

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