Objective
Congenital uterine abnormalities are common and may be associated with developmental renal abnormalities. Mutations of the hepatocyte nuclear factor-1β ( HNF1B) gene are associated with renal and uterine abnormalities. We aimed to study the role of HNF1B mutations in a cohort with congenital uterine abnormalities.
Study Design
We tested 108 probands with uterine abnormalities for HNF1B mutations. We collected clinical information from patient records.
Results
Nine of 108 women (8%) had a mutation or deletion in the HNF1B gene. Abnormal HNF1B was found in 18% of the 50 probands who had both uterine and renal abnormalities but in none of the 58 women with isolated uterine abnormalities.
Conclusion
Mutations of the HNF1B gene are found in women with both uterine and renal abnormalities but are rare in isolated uterine abnormalities. We suggest that HNF1B testing should be performed in patients with both renal and uterine abnormalities, but not in patients with isolated uterine abnormalities.
Congenital genital tract malformations in women have a prevalence in the general population of 0.5-4.3%. During female embryologic development, the 2 Müllerian (paramesonephric) ducts develop into the main genital duct. The caudal Müllerian ducts fuse to form the corpus and cervix of the uterus and the upper vagina. The most common uterine malformations are septate and bicornuate uterus, which are caused by a failure of the Müllerian ducts to fully fuse. These abnormalities are often found incidentally on ultrasound scanning or during surgery. Arcuate, unicornuate, aplastic, and uterus didelphis are also caused by incomplete Müllerian duct fusion; these malformations are rarer but usually are seen clinically. Müllerian duct aplasia leads to vaginal aplasia and rudimentary or absent uterus, and presentation is usually with primary amenorrhea.
Uterine abnormalities are relevant to both obstetrics and fertility medicine. A metaanalysis of 500,000 women found that those with infertility had an increased rate of congenital uterine abnormalities. One-quarter of patients with a known uterine abnormality encounter fertility problems, including higher rates of miscarriage.
Renal tract malformations are associated with uterine malformations. Hereditary urogenital adysplasia (Online Mendelian Inheritance in Man [OMIM] 191830 ) is an autosomal dominant disorder of Müllerian anomalies and renal agenesis, aplasia, or dysplasia. Mayer-Rokitansky-Küster-Hauser syndrome (OMIM 277000 ) is a syndrome that is characterized by congenital absence of vagina, primary amenorrhea, rudimentary cornua (which frequently is associated with urinary tract anomalies and skeletal abnormalities), congenital heart conditions, and inguinal hernia. Embryologically, the Wolffian (mesonephric) and Müllerian (paramesonephric) ducts develop in close proximity.
The hepatocyte nuclear factor-1β (HNF1B) gene located on chromosome 17 is a candidate gene for any syndrome with both uterine and renal tract developmental anomalies. HNF1B is a member of the homeodomain-containing super family of transcription factors. It is important in the tissue-specific regulation of gene expression in a number of organs, which include the kidney, genital tract, pancreas, liver, and gut. It is involved in the early embryogenesis of these organs. Heterozygous mutations and whole gene deletions of the HNF1B gene cause multisystem disease in humans that is referred to as the renal cysts and diabetes syndrome or maturity-onset diabetes of the young, type 5 (OMIM 137920 ). Renal abnormalities are the most consistent phenotype. A wide spectrum of renal developmental disorders that include renal cysts, renal dysplasia, single kidney, and horseshoe kidney are described with renal cysts as being the most common. Genital tract malformations were first reported by Lindner et al in 1999; subsequently, a range of uterine malformations have been described that include bicornuate uterus, uterus didelphis, rudimentary uterus, and vaginal atresia. All cases that have been described to date have been associated with both renal and uterine abnormalities; it is not known whether HNF1B mutations result in isolated uterine abnormalities.
In this study, we report the results of testing 108 women with uterine malformations, both isolated and associated with renal abnormalities, for mutations and whole gene deletions of the HNF1B gene.
Materials and Methods
Subjects
The study population consisted of 108 women with uterine malformations; their clinical details are shown in Table 1 . The subjects were recruited from 3 sources; 22 women were recruited in a secondary referral center after uterine malformations were found at the time of scanning for a gynecologic or obstetric indication or during obstetric and gynecology surgery (none of the women had formal imaging of the renal tract before HNF1B testing); 45 women were from a tertiary referral center and were diagnosed with Mayer-Rokitansky-Küster-Hauser syndrome. Those women with a diagnosis of Mayer-Rokitansky-Küster-Hauser syndrome, all had primary amenorrhea. Clinically, the vagina was short and blind ending, and ultrasound and magnetic resonance imaging confirmed an absent or vestigial uterus. There was no evidence of cervicothoracic somite abnormalities as found in Müllerian duct aplasia, unilateral renal agenesis, and cervicothoracic somite abnormalities (OMIM 601076 ). The 45 patients with Mayer-Rokitansky-Küster-Hauser syndrome had a renal ultrasound scan, serum urea, and electrolytes. All of them had a normal female XX karyotype and normal renal function; however, 12 patients were found to have associated unilateral renal agenesis. The remaining 41 women were noted to have uterine malformations at the time of referral for HNF1B testing (with or without a renal abnormality) and had ultrasound imaging of the renal tract before genetic testing. The analyses of 21 of these patients have previously been described.
| Genital tract abnormality | Renal abnormalities, n | No known renal disease, n | Total, n |
|---|---|---|---|
| Bicornuate uterus | 22 | 16 | 38 |
| Absent genitourinary tract/ovaries | 6 | 6 | |
| Cloacal abnormalities | 2 | 2 | |
| Mayer-Rokitansky-Küster-Hauser syndrome | 12 | 33 | 45 |
| Hemiuterus/ovary | 2 | 1 | 3 |
| Other | 6 | 8 | 14 |
| Total | 50 | 58 | 108 |
HNF1B genetic analysis
Genomic DNA was amplified by the polymerase chain reaction for exons 1-9 of the HNF1B gene. Single-strand sequencing was carried out with the Big Dye Terminator Cycler Sequencing Kit (Applied Biosystems, Warrington, UK). Reactions were analyzed on an ABI 3730 Capillary DNA sequencer (Applied Biosystems, Warrington, UK). Sequences were compared with the published sequence ( NM_000458 ) using Mutation Surveyor Software (SoftGenetics, LLC, State College, PA). Changes in the sequence were checked against published polymorphisms and mutations and for conservation across species.
Whole gene deletions were screened in women without a mutation identified on direct sequencing. We used the previously described method multiplex ligation-dependent probe amplification assay.
Clinical studies
When an HNF1B mutation was identified in the proband, genetic testing was offered to first-degree family members (parents and siblings) initially and to wider family members if available. The medical records were reviewed. Renal ultrasound studies and available biochemical tests of renal function, liver function, urate, magnesium, and blood glucose were reviewed. Biochemical testing was arranged in some subjects.
Results
Genetic analysis of HNF1B
A total of 9 of 108 women (8%) were found to have either a heterozygous HNF1B whole gene deletion (n = 5), p.Met1_Trp557del, detected by multiplex ligation-dependent probe amplification assay or a heterozygous mutation detected by direct sequencing (p.Ala373fs, p.Ser151Pro, p.Val61Gly, Cys273Ser, c.544+3_+6delAAGT; n = 4). Details of 7 of these women have been described previously. Subject DUK1504 harbored a novel mutation at residue 273, where a serine substitutes a cysteine residue. Mutations at this residue have been described previously; the site is conserved in mouse, rat, and xenopus. Subject DUK2395 was found to have a whole gene deletion.
Clinical characteristics
HNF1B mutations or deletions were found in 9 of the 50 women (18%) with both a uterine and a known renal tract abnormality. In contrast, we did not identify a mutation in any of the cases with an isolated uterine abnormality (ie, without a known renal abnormality) or in any of the 45 cases of Mayer-Rokitansky-Küster-Hauser syndrome. Eight of the HNF1B women were referred for HNF1B testing directly, and 1 of these women (DUK1504) who consulted an obstetrician had multiple miscarriages and was tested because of the discovery of renal abnormalities and diabetes mellitus at the time of examination. Only 1 subject (DUK2395) was found directly as a result of obstetric scanning.
The phenotypic data of the 9 HNF1B mutation/deletion probands are shown in Table 2 . The most common uterine malformation among affected probands was a bicornuate uterus, which was identified in 3 of 9 patients (33%). Other uterine abnormalities that were observed were an absent uterus (n = 2), a hemiuterus (n = 2), uterus didelphis (n = 1), and hypoplastic uterus (n = 1). Renal cysts were the most common renal abnormality present in 5 of 9 patients (56%). One woman had a single kidney; 2 women had chronic kidney disease of undefined cause (DUK2997 and DUK0593), and 1 woman (DUK0593) required a renal transplantation at age 45 years. Other features included diabetes mellitus in 4 women (DUK 0593, DUK1504, DUK1826, and DUK2997), abnormal liver function tests in 1 woman (DUK2395), and a congenital pulmonary valve defect and hypoplastic pancreas in 1 woman (DUK2997). Family testing was carried out where possible. Parental DNA samples were available from 2 women with gene deletions, DUK893 and DUK1826. In both cases, the parental samples were normal, which confirmed that the deletion had arisen de novo in the proband. Three women (DUK448, DUK1504, and DUK2395) had sons with renal abnormalities. Genotyping confirmed that they also carried the same mutation as their mothers.
