WT1 splice-site mutations are rarely associated with primary steroid-resistant focal and segmental glomerulosclerosis.

Abstract

BACKGROUND:

Donor splice-site de novo heterozygous mutations in intron 9 of the Wilms' tumor gene (WT1) have been reported in Frasier syndrome, which is defined by the association of focal and segmental glomerulosclerosis (FSGS), male pseudohermaphroditism, and gonadoblastoma. These splice-site mutations alter the WT1 alternative splicing leading to two WT1 isoforms, with (+) or without (-) three amino acids, lysine-threonine-serine (KTS), between zinc fingers 3 and 4. The aim of this work was to investigate the possibility that some cases of primary steroid-resistant nephrotic syndrome associated with FSGS may be caused by WT1 splice-site mutations.

METHODS:

We analyzed WT1 exons 8 and 9 and the surrounding exon/intron boundary DNA sequences in 37 children with nonfamilial primary steroid-resistant nephrotic syndrome. Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to determine the relative ratio of +KTS/-KTS transcripts from immortalized lymphocyte RNA.

RESULTS:

One boy with FSGS and associated pathologies (diaphragmatic hernia, proximal hypospadias, and unilateral testicular ectopia) was found to carry the heterozygous 1228 +4 C-->T splice-site mutation. RT-PCR quantitation of the +KTS/-KTS transcripts from immortalized lymphocyte RNA of this patient showed a diminution of the +KTS/-KTS isoform ratio (0.43), which is identical to that reported in patients with Frasier syndrome. Using the same approach, healthy control subjects have +KTS/-KTS ratios ranging from 1.50 to 2.00.

CONCLUSIONS:

This study expands the range of the phenotypic presentation of the intron 9 splice-site WT1 mutations and adds to the already reported heterogeneity of primary steroid-resistant nephrotic syndromes. We suggest that these mutations are not likely to be a common cause of isolated steroid-resistant nephrotic syndrome, and recommend a WT1 exon 9/intron 9 splice-site study in children with primary steroid-resistant nephrotic syndrome if genital or diaphragmatic anomalies are associated. The identification of such WT1 mutations has practical implications for the management of these patients.

• Authors: E Denamur, N Bocquet, V Baudouin, F Da Silva, R Veitia, M Peuchmaur, J Elion, M C Gubler, M Fellous, P Niaudet, C Loirat
• Journal: Kidney international (Kidney Int) Vol. 57 Issue 5 Pg. 1868-72 (May 2000) ISSN: 0085-2538 [Print] United States
• PMID: 10792605 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Adrenal Cortex Hormones
• DNA-Binding Proteins
• Transcription Factors
• WT1 Proteins

Topics

• Adolescent
• Adrenal Cortex Hormones (therapeutic use)
• Child
• Child, Preschool
• DNA-Binding Proteins (genetics)
• Exons
• Female
• Glomerulosclerosis, Focal Segmental (drug therapy, genetics)
• Humans
• Infant
• Male
• Mutation
• RNA Splicing
• Transcription Factors (genetics)
• WT1 Proteins