Autosomal dominant familial neurohypophyseal diabetes insipidus caused by a novel nonsense mutation in AVP‑NPII gene

  • Authors:
    • Hongbo Yang
    • Kemin Yan
    • Linjie Wang
    • Fengying Gong
    • Zimeng Jin
    • Huijuan Zhu
  • View Affiliations

  • Published online on: June 4, 2019     https://doi.org/10.3892/etm.2019.7645
  • Pages: 1309-1314
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Abstract

Familial neurohypophyseal diabetes insipidus (FNDI) is a rare single‑gene disorder caused by mutations of the arginine vasopressin‑neurophysin II (AVP‑NPII) gene. These changes impair the release of vasopressin from the posterior pituitary gland. In the present study, the AVP‑NPII gene of a Chinese adult patient with central diabetes insipidus, the patient's symptomatic mother and an asymptomatic sister of the patient was sequenced. Examination of the family history revealed cases of FNDI across four generations. Gene sequencing analysis revealed a novel heterozygous mutation, c.268A>T (p.Lys90Ter), in exon 2 of the AVP‑NPII gene, in the patient and the patient's mother, which led to the loss of 6 cysteine residues and aberrant disulfide bonds, which is predicted to alter the mature protein structure. The present study identified a novel heterozygous nonsense mutation of the AVP‑NPII gene associated with FNDI, which broadens the spectrum of known mutations associated with this disorder and contributes to the understanding of its molecular basis.

Introduction

Neurohypopheseal diabetes insipidus is a disorder caused by increased urine production and volume depletion due to vasopressin (AVP) deficiency. Most cases are linked with structural damage of the hypothalamus, pituitary stalk or posterior pituitary gland (1). Familial neurohypophyseal diabetes insipidus (FNDI) is a rare inherited disease that accounts for only 1% of central diabetes insipidus cases (2). The disorder usually presents in early childhood with polyuria and polydipsia, and follow-up evaluation frequently reveals loss of the posterior pituitary bright spot on T1-weighted magnetic resonance imaging (MRI) (35). FNDI is caused by mutations of the arginine vasopressin-neurophysin II (AVP-NPII) gene (GenBank ID, NM_000490.4), which is located on chromosome 20 and encodes a preproprotein that is proteolytically processed to generate multiple products, including AVP, neurophysin II and copeptin (6). Biosynthesis of AVP is tightly regulated by translation and post-translational processes, including enzymatic cleavage of the AVP-neurophysin II prohormone and appropriate secretion of AVP into the circulation upon various stimuli (7,8). Since the publication of the first genetic study on FNDI (9), ~70 mutations have been described and all are located within the 2.5 kb-long AVP-NPII gene. The proposed pathogenic mechanisms include aberrant preprohormone processing leading to the gradual destruction of AVP-secreting cells (10) and mutations that alter the amino acid structure of the mature AVP hormone (11).

The present study reports on a female patient with autosomal dominant FNDI linked to a novel nonsense mutation of AVP-NPII gene and her extended family. The clinical, biochemical and radiological characteristics of the patient were investigated. The novel nonsense mutation was also identified in another affected family member.

Patients and methods

Patients

A 46-year-old Chinese woman was referred to Peking Union Medical College Hospital (Beijing, China) for evaluation of acute urinary retention. A urinary catheter was placed to alleviate severe bladder distension. She reported having polyuria and polydipsia since age 13, but had not sought any medical care, as she always had access to water. The patient was born at term without any complications and had a normal pubescence. A total of 12 additional family members spanning four generations, including the patient's mother and younger brother, also had teenage-onset of polyuria and polydipsia. Daily urine volumes varied from 6.0 to 15.0 liters. No mental retardation or delay in puberty had been identified. The average final body height was 160.1 cm for females and 175.2 cm for male members of the family. The pedigree of the family is presented in Fig. 1.

Clinical, laboratory and radiological assessments

Clinical data were collected in accordance with the Declaration of Helsinki. Written informed consent was obtained from the patient (IV-8), the patient's mother (III-7) and an asymptomatic sister of the patient (IV-7). A water deprivation test followed by the administration of vasopressin was performed to diagnose central diabetes insipidus as described previously (12). Enhanced MRI of the hypothalamo-hypophyseal area and pelvis was performed. The residual urine volume was measured by performing an ultrasound scan of the bladder.

Genomic DNA extraction, amplification and sequencing of the AVP-NPII gene

The AVP-NPII gene was analyzed by direct sequencing from genomic DNA extracted from leucocytes of peripheral blood with the QIAamp DNA Mini kit (Qiagen GmbH). In brief, PCR was performed in a 40-µl reaction volume containing 100 ng genomic DNA, 20 µl 2X GC PCR buffer, 0.1 µM of each dNTP, 0.1 µM of each primer and 2.5 units of rTaq polymerase (Takara Bio, Inc.) in a thermocycler (ABI 9700; Applied Biosystems; Thermo Fisher Scientific, Inc.). All genomic DNA was denatured at 94°C for 10 min and amplified with 35 cycles. For exon 1, the cycles were programmed as 94°C for 30 sec, 60°C for 30 sec and 72°C for 40 sec. The cycling conditions for exons 2 and 3 were programmed as follows: Module 1 was 94°C for 5 min, 65°C for 5 min and 74°C for 5 min (1 cycle); module 2 was 94°C for 1 min, 65°C for 1 min and 74°C for 4 min (35 cycles); module 3 was 74°C for 10 min; module 4 was a hold at 4°C. Primers for amplification and sequencing of the AVP-NPII gene are provided in Table I. Amplified products were detected by agarose gel electrophoresis and sequenced using an ABI 3730 DNA analyzer (Applied Biosystems; Thermo Fisher Scientific, Inc.).

Table I.

Primer sequences for PCR of the arginine vasopressin-neurophysin II gene.

Table I.

Primer sequences for PCR of the arginine vasopressin-neurophysin II gene.

Exon/directionSequences (5′-3′)
1
  Forward ATGATCCCCTGCACAGACAG
  Reverse CTGCCCAGCCATGCCATG
2
  Forward TCGCTGCGTTCCCCTCCAACCCCTCGACTC
  Reverse CGCCCCCCCCCAGGCCCGCCCCCGCCGCGC
3
  Forward CCCAGGCGCCCGTGCTCACACGTCCTCCCG
  Reverse CCTCTCTCCCCTTCCCTCTTCCCGCCAGAG

Three-dimensional structural models of the predicted wild-type and mutant proteins were generated and comparisons between the proteins were performed using the PHYRE2 Protein Fold Recognition Server database (http://wwwsbg.bio.ic.ac.uk/phyre2) and the SWISS-MODEL protein structure homology-modelling server (http://swissmodel.expasy.org) as reported previously (5).

Results

Clinical and MRI assessments

Diabetes insipidus was confirmed via a standard water deprivation test. After 8 h of water deprivation, the plasma osmolality rose from 301 to 315 mOsm/kg and the urine osmolality rose from 50 to 65 mOsm/kg. 4 U vasopressin was subsequently injected intramuscularly. Following 2 h, the plasma osmolality decreased from 315 to 302 mOsm/kg and the urine osmolality increased from 65 to 587 mOsm/kg. As presented in Fig. 2A, the cranial MRI revealed a high signal region in the posterior lobe of the pituitary gland. Serum cortisol, thyroid function, growth hormone levels, insulin-like growth factor 1 and estrogen were all within normal ranges. Pelvic MRI revealed a significantly enlarged urinary bladder (Fig. 2B). The daily urine output decreased from 15 l to 2 l after 1 week of treatment with 100 µg 1-deamino-8-D-arginine-vasopressin three times per day. The dosage was then tapered to 50 µg, which was administered 3 times per day and maintained thereafter. The residual urine volume decreased from 1,250 to 4 ml and the urinary catheter was removed.

PCR and sequencing

The AVP-NPII genes were sequenced from the patient, the patient's mother and a sister of the patient. Sequence analyses of the patient's entire AVP-NPII coding region revealed a novel heterogeneous nonsense mutation at codon 268 (c.268A>T), which results in a substitution in exon 2 of Lys (AAG) with a stop codon (TAG) and corresponds to lysine 90 of the NPII moiety (p.Lys90Ter) (Fig. 3A). The same mutation was identified in the patient's mother (Fig. 3B), but not in the patient's sister, who had a normal phenotype (Fig. 3C). The 3-D structures of the wild-type and mutant (p.Lys90Ter) AVP-NPII proteins were modeled using the above-mentioned computational servers. As presented in Fig. 4, the Lys90Ter mutation is located in the middle of NPII and leads to the loss of 74 amino acids, including 6 cysteine residues. The loss of cysteine residues results in aberrant disulfide bonds, which is expected to alter the protein structure.

Discussion

The present study reports on a novel p.Lys90Ter mutation identified in exon 2 of the AVP-NPII gene that is linked with FNDI. The pedigree examined included cases spanning four generations, with no apparent gender preponderance among affected individuals. Similar to the observations of previously published studies on FNDI, the affected individuals in the present study were normal at birth and gradually developed symptoms of vasopressin deficiency beginning in childhood or adolescence (13). None of the subjects had any mental deficits or impaired pubescent development.

FNDI is a rare, single-gene disorder caused by mutations in the 2.5-kb AVP-NPII gene located in chromosome region 20p13 (14,15). The AVP-NPII gene has three exons: Exon 1 encodes a signal peptide, AVP, and the NH2-terminal portion of neurophysin II, exon 2 encodes the central region of neurophysin II and exon 3 encodes the COOH-terminal region of neurophysin II and copeptin. AVP is synthesized in the supraoptic nucleus and paraventricular nucleus of the hypothalamus and then packaged into neurosecretory vesicles along with its carrier protein neurophysin II. It is then transported axonally to the neurohypophysis. Most of the mutations reported to be associated with FNDI are located in the region encoding the NPII moiety, which is the intracellular binding protein for AVP. Several mutations are localized to the coding region for signaling peptide or AVP per se. The mutant NPII is assumed to interfere with axonal transport of intracellular AVP proteolysis (16,17).

A total of 7 mutations spanning all 3 exons of the AVP-NPII gene have been previously described in Chinese populations (Table II) (1820), including 3 missense mutations in exon 2. To the best of our knowledge, the present study is the first to report on a nonsense mutation in exon 2 of the AVP-NPII gene in Chinese individuals. The mutation results in a preterm stop codon and thus a truncated NPII moiety. Wild-type pro-vasopressin has 164 amino acids and 7 disulfide bonds between all 14 cysteine residues (21). The mutant NPII loses 6 of these cysteine residues and the resultant aberrant disulfide bonds cause misfolding of the prohormone. As a result, the prohormone is likely retained within the endoplasmic reticulum and exceeds its capacity to tolerate the ‘unfolded protein response’, causing stress that may trigger apoptosis (22,23). However, further investigations are required to verify the molecular mechanisms underlying FNDI. It may be hypothesized that FNDI follows a pattern of autosomal dominant inheritance, which is consistent in the present pedigree.

Table II.

Arginine vasopressin-neurophysin II gene mutations in familial neurohypophyseal diabetes insipidus reported in the Chinese population.

Table II.

Arginine vasopressin-neurophysin II gene mutations in familial neurohypophyseal diabetes insipidus reported in the Chinese population.

First author (year)Coding regioncDNA mutationAmino acid changeMutation typeMode of inheritanceFamily history(Refs.)
Tian (2016)Exon 1c.2delTp.M1_T4delFrameshift mutationAutosomal dominantYes(18)
Tian (2016)Exon 1c.50C>Ap.S17YMissense mutationAutosomal dominantYes(18)
Tian (2016)Exon 1c.52-54delTCCp.S18delFrameshift mutationAutosomal dominantNo(18)
Tian (2016)Exon 2c.127C>Gp.P43AMissense mutationAutosomal dominantNo(18)
Tian (2016)Exon 3c.329C>Ap.C110YMissense mutationAutosomal dominantNo(18)
Ye (2013)Exon 2c.1516G>Tp.G17VMissense mutationAutosomal dominantYes(19)
Luo (2012)Exon 2c.193T>Ap.C65SMissense mutationAutosomal dominantYes(20)
Present studyExon 2c.268A>Tp.Lys90TerNonsense mutationAutosomal dominantYes

[i] cDNA, complementary DNA.

Previous studies have described the MRI presentation of subjects with FNDI. In one study, the presence of a bright spot in the posterior lobe appeared to vary between members of the same family (5). In another case series, such a spot was entirely absent from all 13 patients (24). The MRI of the patient in the current study revealed a bright spot on the posterior lobe of pituitary gland. More serious urological complications are uncommon in these patients, as they retain a limited capacity to secrete AVP during severe dehydration.

In conclusion, the present study identified a novel nonsense mutation in the AVP-NPII gene linked with NDI in a Chinese patient whose family members shared a history of polyuria and polydipsia across four generations. This heterogeneous Lys90Ter mutation is located in the middle of NPII and leads to loss of 6 cysteine residues and aberrant disulfide bonds, which is expected to alter the mature protein structure. Although a number of studies have described variant mutations of NPII in FNDI, further elucidation of the molecular mechanisms underlying specific mutant interference with the axonal transport of intracellular AVP proteolysis are required.

Acknowledgements

Not applicable.

Funding

This work was supported by the Special Research Fund for Central Universities, Peking Union Medical College (grant no. 2017PT31004) and the CAMS Innovation Fund for Medical Science (grant no. CAMS-2016-I2M-1-002□2016-I2M-1-008).

Availability of data and materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Authors' contributions

HY analyzed and interpreted the patient data and wrote the primary manuscript. KY performed the PCR experiments. LW collected the blood samples of the patient and the patient's relatives and analyzed the gene sequencing data. FG supervised the experiments and data analysis. ZJ helped to interpret the patient's clinical data. HZ revised the primary manuscript and was a major contributor in writing the manuscript.

Ethics approval and consent to participate

The present study was approved by the ethics committee of Peking Union Medical College Hospital (Beijing, China).

Patient consent for publication

Written informed consent was obtained from the patient, the patient's mother and an asymptomatic sister prior to genetic testing and the publication of data and images in the present study.

Competing interests

The authors declare that they have no competing interests.

Glossary

Abbreviations

Abbreviations:

AVP-NPII

arginine vasopressin-neurophysin II

FNDI

familial neurohypophyseal diabetes insipidus

References

1 

Baylis PH and Robertson GL: Vasopressin function in familial cranial diabetes insipidus. Postgrad Med J. 57:36–40. 1981. View Article : Google Scholar : PubMed/NCBI

2 

Deniz F, Acar C, Saglar E, Erdem B, Karaduman T, Yonem A, Cagiltay E, Ay SA and Mergen H: Identification of a novel deletion in AVP-NPII gene in a patient with central diabetes insipidus. Ann Clin Lab Sci. 45:588–592. 2015.PubMed/NCBI

3 

Saglar E, Karaduman T, Ozcan M, Erdem B, Oflaz O, Sahin D, Deniz F, Ay AS and Mergen H: Identification of novel mutations in AVP-NPII gene. FEBS J. 283:1312016.

4 

Elias PC, Elias LL, Torres N, Moreira AC, Antunes-Rodrigues J and Castro M: Progressive decline of vasopressin secretion in familial autosomal dominant neurohypophyseal diabetes insipidus presenting a novel mutation in the vasopressin-neurophysin II gene. Clin Endocrinol (Oxf). 59:511–518. 2003. View Article : Google Scholar : PubMed/NCBI

5 

Turkkahraman D, Saglar E, Karaduman T and Mergen H: AVP-NPII gene mutations and clinical characteristics of the patients with autosomal dominant familial central diabetes insipidus. Pituitary. 18:898–904. 2015. View Article : Google Scholar : PubMed/NCBI

6 

Gainer H, Yamashita M, Fields RL, House SB and Rusnak M: The magnocellular neuronal phenotype: Cell-specific gene expression in the hypothalamo-neurohypophysial system. Prog Brain Res. 139:1–14. 2002. View Article : Google Scholar : PubMed/NCBI

7 

Murphy D and Wells S: In vivo gene transfer studies on the regulation and function of the vasopressin and oxytocin genes. J Neuroendocrinol. 15:109–125. 2003. View Article : Google Scholar : PubMed/NCBI

8 

Repaske DR, Phillips JA III, Kirby LT, Tze WJ, D'Ercole AJ and Battey J: Molecular analysis of autosomal dominant neurohypophyseal diabetes insipidus. J Clin Endocrinol Metab. 70:752–757. 1990. View Article : Google Scholar : PubMed/NCBI

9 

Ito M, Mori Y, Oiso Y and Saito H: A single base substitution in the coding region for neurophysin II associated with familial central diabetes insipidus. J Clin Invest. 87:725–728. 1991. View Article : Google Scholar : PubMed/NCBI

10 

Christensen JH and Rittig S: Familial neurohypophyseal diabetes insipidus-an update. Semin Nephrol. 26:209–223. 2006. View Article : Google Scholar : PubMed/NCBI

11 

Willcutts MD, Felner E and White PC: Autosomal recessive familial neurohypophyseal diabetes insipidus with continued secretion of mutant weakly active vasopressin. Hum Mol Genet. 8:1303–1307. 1999. View Article : Google Scholar : PubMed/NCBI

12 

Trimpou P, Olsson DS, Ehn O and Ragnarsson O: Diagnostic value of the water deprivation test in the polyuria-polydipsia syndrome. Hormones. 16:414–422. 2017.PubMed/NCBI

13 

Rittig S, Robertson GL, Siggaard C, Kovács L, Gregersen N, Nyborg J and Pedersen EB: Identification of 13 new mutations in the vasopressin-neurophysin II gene in 17 kindreds with familial autosomal dominant neurohypophyseal diabetes insipidus. Am J Hum Genet. 58:107–17. 1996.PubMed/NCBI

14 

Sausville E, Carney D and Battey J: The human vasopressin gene is linked to the oxytocin gene and is selectively expressed in a cultured lung cancer cell line. J Biol Chem. 260:10236–10241. 1985.PubMed/NCBI

15 

Rao VV, Löffler C, Battey J and Hansmann I: The human gene for oxytocin-neurophysin I (OXT) is physically mapped to chromosome 20p13 by in situ hybridization. Cytogenet Cell Genet. 61:271–273. 1992. View Article : Google Scholar : PubMed/NCBI

16 

Christensen JH, Siggaard C, Corydon TJ, Robertson GL, Gregersen N, Bolund L and Rittig S: Impaired trafficking of mutated AVP prohormone in cells expressing rare disease genes causing autosomal dominant familial neurohypophyseal diabetes insipidus. Clin Endocrinol (Oxf). 60:125–136. 2004. View Article : Google Scholar : PubMed/NCBI

17 

Kobayashi H, Fujisawa I, Ikeda K, Son C, Iwakura T, Yoshimoto A, Kasahara M, Ishihara T and Ogawa Y: A novel heterozygous missense mutation in the vasopressin moiety is identified in a Japanese person with neurohypophyseal diabetes insipidus. J Endocrinol Invest. 29:252–256. 2006. View Article : Google Scholar : PubMed/NCBI

18 

Tian D, Cen J, Nie M and Gu F: Identification of five novel arginine vasopressin gene mutations in patients with familial neurohypophyseal diabetes insipidus. Int J Mol Med. 38:1243–1249. 2016. View Article : Google Scholar : PubMed/NCBI

19 

Ye D, Dong F, Lu W, Zhang Z, Lu X, Li C and Liu Y: A missense mutation in the arginine-vasopressin neurophysin-II gene causes autosomal dominant neurohypophyseal diabetes insipidus in a Chinese family. Clin Endocrinol (Oxf). 78:920–925. 2013. View Article : Google Scholar : PubMed/NCBI

20 

Luo Y, Wang B, Qiu Y, Zhang C, Jin C, Zhao Y, Zhu Q and Ma X: Clinical and molecular analysis of a Chinese family with autosomal dominant neurohypophyseal diabetes insipidus associated with a novel missense mutation in the vasopressin-neurophysin II gene. Endocrine. 42:208–213. 2012. View Article : Google Scholar : PubMed/NCBI

21 

Baglioni S, Corona G, Maggi M, Serio M and Peri A: Identification of a novel mutation in the arginine vasopressin-neurophysin II gene affecting the sixth intrachain disulfide bridge of the neurophysin II moiety. Eur J Endocrinol. 151:605–611. 2004. View Article : Google Scholar : PubMed/NCBI

22 

Arima H, Morishita Y, Hagiwara D, Hayashi M and Oiso Y: Endoplasmic reticulum stress in vasopressin neurons of familial diabetes insipidus model mice: Aggregate formation and mRNA poly(A) tail shortening. Exp Physiol. 99:66–71. 2014. View Article : Google Scholar : PubMed/NCBI

23 

Ahner A and Brodsky JL: Checkpoints in ER-associated degradation: Excuse me, which way to the proteasome? Trends Cell Biol. 14:474–478. 2004. View Article : Google Scholar : PubMed/NCBI

24 

Gudinchet F, Brunelle F, Barth MO, Taviere V, Brauner R, Rappaport R and Lallemand D: MR imaging of the posterior hypophysis in children. AJR Am J Roentgenol. 153:351–354. 1989. View Article : Google Scholar : PubMed/NCBI

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Spandidos Publications style
Yang H, Yan K, Wang L, Gong F, Jin Z and Zhu H: Autosomal dominant familial neurohypophyseal diabetes insipidus caused by a novel nonsense mutation in AVP‑NPII gene. Exp Ther Med 18: 1309-1314, 2019
APA
Yang, H., Yan, K., Wang, L., Gong, F., Jin, Z., & Zhu, H. (2019). Autosomal dominant familial neurohypophyseal diabetes insipidus caused by a novel nonsense mutation in AVP‑NPII gene. Experimental and Therapeutic Medicine, 18, 1309-1314. https://doi.org/10.3892/etm.2019.7645
MLA
Yang, H., Yan, K., Wang, L., Gong, F., Jin, Z., Zhu, H."Autosomal dominant familial neurohypophyseal diabetes insipidus caused by a novel nonsense mutation in AVP‑NPII gene". Experimental and Therapeutic Medicine 18.2 (2019): 1309-1314.
Chicago
Yang, H., Yan, K., Wang, L., Gong, F., Jin, Z., Zhu, H."Autosomal dominant familial neurohypophyseal diabetes insipidus caused by a novel nonsense mutation in AVP‑NPII gene". Experimental and Therapeutic Medicine 18, no. 2 (2019): 1309-1314. https://doi.org/10.3892/etm.2019.7645