The Wilms’ tumor suppressor gene (WT1), located at chro-
mosome 11p13, has 10 exons, spans -50 kb, and encodes a
zinc-finger-transcription factor presumed to regulate the ex-
pression of numerous target genes through DNA binding (1).
WT1 was initially identified as a gene inactivated in Wilms’
tumor, although the estimated percentage of Wilms’ tumors
(WTs) with WT1mutations is only 10-15%. Investigations
of WT1 have revealed the normal physiologic functions of
this gene in embryogenesis, gonadogenesis and nephrogen-
esis (1). WT1has been shown to play a role in kidney induc-
tion (2) and during later steps of nephrogenesis (3), and there
are suggestions that WT1 may play an important role in the
maintenance of normal podocyte function (4).
Besides Wilms’ tumor, a number of human diseases have
been shown to be associated with mutations of the WT1 gene
(5).Genital abnormalities are noted in three of these disorders,
WAGR syndrome (Wilms’ tumor, aniridia, genitourinary
malformation, and mental retardation), Denys-Drash syn-
drome (DDS), and Frasier syndrome (FS), and the analysis of
WT1 knockout mice also suggested a fundamental role of
WT1in gonad development (6). Wilhelm and Englert report-
ed that the WT1 regulates early gonad development by acti-
vation of steroidogenesis factor 1, Sf1, which encodes an or-
phan nuclear receptor that regulates the expression of several
genes involved in steroidogenesis and gonadal development (7).
DDS traditionally encompasses patients with the triad of
congenital nephrotic syndrome leading to end-stage renal
failure (ESRF), XY pseudohermaphroditism and Wilms’ tu-
mor (8, 9). Subsequent reports described patients with incom-
plete forms of this syndrome (10-12), and the definition of
DDS has now been widened to include XY individuals with
mild to severe genital anomalies as well as XX individuals
displaying nephropathy and WT (13). The nephropathies in
DDS are characterized by the histological finding of diffuse
mesangial sclerosis (DMS), a finding also described in some
cases of congenital nephrotic syndrome (isolated diffuse me-
sangial sclerosis, IDMS). Analysis of genotype-phenotype cor-
relation in IDMS suggests that at least some IDMS patients
have a variant form of DDS due to WT1mutations (14).
Attempts to correlate the phenotype of DDS and different
WT1 mutations did not provide clear-cut results (15), and
no correlation could be established between any particular
mutation and the occurrence of Wilms’ tumor. However, anal-
ysisof a large number of patients might provide clues to the
role of each mutation, and might help in understanding the
normal physiology of nephrogenesis and the prediction for
In this report, we present two cases of IDMS with different
WT1 gene mutations that had previously been reported in
association with DDS.
Hyewon Hahn, Young Mi Cho*,
Young Seo Park, Han Wook You,
Hae Il Cheong
Department of Pediatrics and Pathology*, Asan
Medical Center, University of Ulsan College of
Medicine, Seoul; Department of Pediatrics
National University Children’s Hospital, Seoul, Korea
Address for correspondence
Young Seo Park, M.D.
Department of Pediatrics, Asan Medical Center,
University of Ulsan College of Medicine, 388-1
Pungnap-dong, Songpa-gu, Seoul 138-736, Korea
Tel : +82.2-3010-3376, Fax : +82.2-473-3725
E-mail : firstname.lastname@example.org
J Korean Med Sci 2006; 21: 160-4
Copyright � The Korean Academy
of Medical Sciences
Two Cases of Isolated Diffuse Mesangial Sclerosis with WT1
Here we report two cases of isolated diffuse mesangial sclerosis (IDMS) with early
onset end-stage renal failure. These female patients did not show abnormalities of
the gonads or external genitalia. Direct sequencing of WT1 PCR products from ge-
nomic DNA identified WT1 mutations in exons 8 (366 Arg>His) and 9 (396 Asp>Tyr).
These mutations have been reported previously in association with Denys-Drash
syndrome (DDS) with early onset renal failure. Therefore we suggest that, at least
in part, IDMS is a variant of DDS and that investigations for the WT1 mutations should
be performed in IDMS patients. In cases with identified WT1 mutations, the same
attention to tumor development should be required as in DDS patients, and kary-
otyping and serial abdominal ultrasonograms to evaluate the gonads and kidney
Key Words : Denys-Drash Syndrome; Diffuse Mesangial Sclerosis; WT1 Proteins; Genes, Wilms Tumor
Received : 22 December 2004
Accepted : 7 January 2005
IDMS with WT1 Mutation
A 76-day-old girl was referred for evaluation of leg edema
and albuminuria. She was born at 37+1weeks’ gestational age
with a birth weight of 2,500 g. Placenta weight was 450 g.
Physical examination on admission revealed generalized ede-
ma, ascites and normal female external genitalia. Laboratory
findings showed; hemoglobin, 8.2 g/dL; cholesterol, 147 mg/
dL; total serum protein, 3.5 g/dL; serum albumin, 2.1 g/dL;
serum creatinine, 1.7 mg/dL; BUN, 27 mg/dL; total calcium,
5.6 mg/dL; phosphorus, 11.7 mg/dL; sodium, 116 mEq/L;
potassium, 6.0 mEq/L; chloride 102 mEq/L; tCO2 5.7 mEq/L.
Urinalysis revealed albuminuria and hematuria. She was anu-
ric after admission, and peritoneal dialysis was commenced.
Ultrasound examination revealed enlarged kidneys with in-
creased parenchymal echogenicity. A renal biopsy was per-
formed at the age of 111 days, and 30 glomeruli were exam-
ined. Light microscopy showed diffuse mesangial sclerosis
(Fig. 1) and cortical tubular dilatation and microcyst forma-
tion. Subcapsular tubular atrophy and small immature glo-
meruli were also seen. Karyotype analysis showed 46 chro-
mosomes, including XX. A WT1 mutation was identified
by direct sequencing of a WT1 PCR product obtained from
genomic DNA from white blood cells. Analysis of the WT1
exon 8 sequence revealed the presence of a heterozygous G to
A base substitution, converting 366Arg to 366His (Fig. 2). This
base substitution was absent in both parents. The patient is
now 13 months old, and is well and on peritoneal dialysis,
expecting renal transplantation. Abdominal ultrasonogram
has revealed no mass lesions in the kidney or ovary.
A 26-day-old girl was referred for evaluation of renal fail-
ure. She was born at 38+5weeks’ gestational age with a birth
weight of 3,200 g. She was well until two days before admis-
sionwhen she developed generalized tonic clonic seizure. At
a local clinic, hypocalcemia, hyperkalemia and azotemia were
detected and she was referred to us. On admission, generalized
edema was noted. Her external genitalia were normal female.
Laboratory findings showed: hemoglobin, 9.8 g/dL; choles-
terol, 120 mg/dL; total serum protein, 3.7 g/dL; serum albu-
Fig. 2. Sequence analysis of WT1 exon 8 from the DNA of patient
1, with a G>A alteration changing amino acid 366 from Arg to His.
Fig. 1. Renal biopsy showing glomeruli with diffuse mesangial
sclerosis (PAS, ×200).
Fig. 3.Renal biopsy showing small glomeruli with mesangial scle-
rosis and collapsed capillary lumens. Some tubules are dilated
and contain protein casts, with epithelial degeneration and regen-
erativeactivity (PAS, ×400).
T T T T C T C G T T C A G A C C A G C T C A A
80 140 150
H. Hahn, Y.M. Cho, Y.S. Park, et al.
min, 1.5 g/dL; BUN, 75 mg/dL; serum creatinine, 4.1 mg/dL;
total calcium, 5.9 mg/dL; phosphorus, 12.7 mg/dL; sodium,
136 mEq/L; potassium, 5.5 mEq/L; chloride, 113 mEq/L;
tCO2 7.8 mEq/L. Albuminuria and hematuria were detected.
An ultrasonogram revealed enlarged kidneys with increased
parenchymal echogenicity and poor corticomedullary differ-
entiation. A renal biopsy was performed at the age of 29 days
and light microscopy showed small glomeruli with various
degrees of mesangial sclerosis (Fig. 3). The tubules were dilat-
edwith regenerative activity. Her karyotype was 46 XX. Anal-
ysis of the sequence of WT1 exon 9 revealed the presence of
a heterozygous G to T base substitution, converting 396Asp to
396Tyr, and a heterozygous 395 Ser (TCC) > Ser (TCA) poly-
morphism (Fig. 4). Both parents showed normal sequence
at these sites. Peritoneal dialysis was commenced with a tem-
poraryshift to hemodiafiltration because of dialysate leakage
at the exit site. Sustained hypertension (120/80 mmHg) res-
ponded to an angiotensin-converting enzyme inhibitor. She
was maintained on total parenteral nutrition due to uncon-
trolled chylothorax that resulted from internal jugular vein
catheterization, and the patient died at the age of six months
due to multiple serious infections and failure to thrive. Autopsy
was not performed.
These two patients showed isolated diffuse mesangial scle-
rosis without genital abnormalities. The mutation present in
the second patient was previously reported in a DDS patient
with early onset ESRF resulting from DMS, ambiguous gen-
italia, and a 46 XY karyotype. Autopsy showed a streak go-
nad and nephroblastomatosis, but no WTs were revealed (16).
As in our second patient, this boy reached ESRF within a few
weeks. Considering that ESRF in DMS is reached within a
few months or years (17), early onset ESRF in patients is noted
as a feature of this mutation. The mutation in the first patient
was also previously reported in a DDS patient (46 XY, female
genitalia, streak gonad, DMS, gonadoblastoma, without WT)
It is well known that WT1 has many roles during gonado-
genesis, and since WT1 is expressed in the same cell lineage
as SRY, the Y-located testis determinant, WT1 may be act-
ing upstream to SRY during development of the genital rid-
ge; perhaps controlling SRYexpression, or interacting directly
with SRY during sex determination, or functioning immedi-
ately downstream of SRY (19). WT1-null mutant mice of
both sexes fail to develop kidneys and gonads, indicating that
WT1acts upstream of the sex-determining decision (6).
Frasier syndrome (FS) is another distinctive disease associ-
ated with WT1 mutation, characterized by male pseudoher-
maphroditism and nephropathy with late onset ESRF, and a
frequent association with gonadoblastoma (20). Molecular
analysis of a familial case of FS has been described, which pro-
videda clue to WT1’s effects on gonadogenesis. Two sisters in
their late teens showed signs of renal disease and each sister
has a donor splice-site mutation that was predicted to result
in an imbalance of the KTS+/KTS- isoforms. One sister was
46 XY, with complete gonadal dysgenesis with normal female
phenotype, while the other was 46 XX, with apparently nor-
mal ovarian development and function. This suggests that
either WT1 has a male-specific function in sex determination
or that testis formation is much more sensitive to dosage ef-
fects than ovarian formation (21).
Our two cases are female with karyotype 46 XX, which
might be the reason for the absence of gonadal abnormalities,
and we suspect that if a patient is born with karyotype 46
XY, there may be a possibility of DDS development. Although
male patients have been described (14, 22), IDMS most often
occurs in females; however, the percentage of patients with
WT1 mutation-positive IDMS, the sex ratio and the associ-
ated risk of Wilms’ tumor are still unknown. A recent study
of seven Japanese IDMS patients reported a low rate of WT1
mutation (2/7) and a low risk of Wilms’ tumor (0/7) (23). The
mutations observed in these Japanese patients were different
from those observed in the previous reports of DDS, and in
the removed kidneys, nephrogenic nests were not found.
Therefore, it was concluded that in IDMS with WT1 muta-
tions, the risk of Wilms’ tumor might not be very high. Our
report is limited to two patients, but both mutations were
already associated with DDS, and the early onset ESRF in
patients with the 396 Asp (GAC) > Tyr (TAC) mutation is
distinctively similar. This supports the concept that, at least
in part, IDMS is a variant form of DDS, and we suggest that
IDMS patients require the same attention as DDS patients
because of the possible association with Wilms’ tumor and/or
Hu et al. (24) recently reported two boys with incomplete
DDS with WT1 mutations who underwent prophylactic bi-
Fig. 4. Sequence analysis of WT1 exon 9 from the DNA of patient
2, with a heterozygous G>T alteration changing amino acid 396
from Asp to Tyr, and a heterozygous polymorphism of 395 Ser
(TCC) > Ser (TCA).
T T C A G G T G G T N T G A C C G G G A G A A
70 80 90
IDMS with WT1 Mutation
lateral nephrectomy, and the removed kidneys showed ne-
phroblastomatosis, which has malignant potential. Initial
renal biopsy and imaging studies did not demonstrate these
findings. The authors suggested that missense mutations in
exons 8 and 9 of WT1can be regarded as risk factors for devel-
opmentof Wilms’ tumor and proposed prophylactic bilater-
al nephrectomy and early renal transplantation. It is still de-
batable whether prophylactic nephrectomies should be car-
ried out in all children with DMS before renal transplanta-
tion, and Schumacher et al. (15) suggested that regular renal
imaging might be necessary to evaluate the need for bilateral
nephrectomy. Considering the clinical courses of the patients
in the previous reports, our patients also might have had the
possibility of malignant transformation, but we chose regu-
lar renal and gonadal imaging rather than prophylactic ne-
phrectomy, and three-monthly ultrasonogram until death
did not show evidence of malignancy in the second patient.
The first patient is well on peritoneal dialysis with no sign
of malignancy on three-monthly screening and we are con-
sidering of nephrectomy at the time of transplantation.
The reason for the heterogeneity of the clinical features of
patients with WT1mutations is not yet clear, and we suggest
that a classification based on genetic diagnosis rather than
syndromatic diagnosis might be more applicable for the pre-
diction of outcome, and routine genetic analysis to detect
WT1 mutation should be applied to all IDMS patients. If
WT1 mutation is documented, karyotyping and serial abdo-
minal ultrasonographies are warranted for the evaluation of
tumor development in the gonad and kidney, and the analy-
sis of genotype-phenotype correlations should be continued.
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