A novel heterozygous missense mutation in the vasopressin moiety is identified in a Japanese person with neurohypophyseal diabetes insipidus

Genomic analysis of arginine vasopressin gene in riverine buffalo reveals its potential association with silent estrus behavior

BACKGROUND

Poor estrus expression behavior causes suboptimal reproductive efficiency through poor conception rate. Various signaling pathways are involved in estrus expression but arginine vasopressin (AVP) gene with oxytocin predominantly regulates estrus behavior. This study aimed to perform genomic characterization and evolutionary dynamics of AVP gene through association testing of the novel polymorphic loci and comparative genomic analysis to explore the potential effect of AVP gene on estrus behavior of Nili-Ravi buffaloes.

METHODS AND RESULTS

198 Nili-Ravi buffaloes were screened for the quest of novel polymorphism in the AVP gene. In exon-1, five polymorphic sites were detected including deletion of two (c.47delA and c.57delA) nucleotides that caused drastic variation in subsequent amino acid sequence due to frame shift including functional short peptide of nine residues. The 3-D structure revealed a loss of transmembrane loop between 16 and 31 residues in Nili-Ravi buffalo AVP protein sequence, suggesting that missing loop apparently reduced the gene functionality in Nili-Ravi buffalo by inhibiting cellular reactions and muting the animal estrus cyclicity. Three polymorphisms detected in AVP gene were significantly associated with silent estrus (P < 0.05). The comparative genomic analysis revealed that AVP gene is present on chromosome 14 having one conserved motif (Neurohypophysial) in buffalo.

CONCLUSIONS

This study suggested the potential use of polymorphic sites as promising genetic markers for selection of buffaloes with pronounced estrus expression.

Central Diabetes Insipidus Caused by Arginine Vasopressin Gene Mutation: Report of a Novel Mutation and Review of Literature

Familial neurohypophyseal diabetes insipidus (FNDI) is an autosomal dominant hereditary disorder characterized by severe polydipsia and polyuria that usually presents in early childhood. In this study, we describe a new arginine vasopressin (AVP) gene mutation in an ethnic German family with FNDI and provide an overview of disease-associated AVP-gene mutations that are already described in literature. Three members of a German family with neurohypophyseal diabetes insipidus were studied. Isolated DNA from peripheral blood samples was used for mutation analysis by sequencing the whole coding region of AVP-NPII gene. Furthermore, we searched the electronic databases MEDLINE (Pubmed) as well as HGMD, LOVD-ClinVar, db-SNP and genomAD in order to compare our cases to that of other patients with FNDI. Genetic analysis of the patients revealed a novel heterozygote missense mutation in exon 2 of the AVP gene (c.274T>G), which has not yet been described in literature. We identified reports of more than 90 disease-associated mutations in the AVP gene in literature. The novel mutation of the AVP gene seems to cause FNDI in the presented German family. Similar to our newly detected mutation, most mutations causing FNDI are found in exon 2 of the AVP gene coding for neurophysin II. Clinically, it is important to think of FNDI in young children presenting with polydipsia and polyuria.

Forty-One Individuals With Mutations in the AVP-NPII Gene Associated With Familial Neurohypophyseal Diabetes Insipidus

CONTEXT

Familial neurohypophyseal diabetes insipidus is a rare disease produced by a deficiency in the secretion of antidiuretic hormone and is caused by mutations in the arginine vasopressin gene.

OBJECTIVE

Clinical, biochemical, and genetic characterization of a group of patients clinically diagnosed with familial neurohypophyseal diabetes insipidus, 1 of the largest cohorts of patients with protein neurophysin II (AVP-NPII) gene alterations studied so far.

DESIGN

The AVP-NPII gene was screened for mutations by PCR followed by direct Sanger sequencing in 15 different unrelated families from Spain.

RESULTS

The 15 probands presented with polyuria and polydipsia as the most important symptoms at the time of diagnosis. In these patients, the disease was diagnosed at a median of 6 years of age. We observed 11 likely pathogenic variants. Importantly, 4 of the AVP-NPII variants were novel (p.(Tyr21Cys), p.(Gly45Ser), p.(Cys75Tyr), p.(Gly88Cys)).

CONCLUSIONS

Cytotoxicity seems to be due to consequences common to all the variants found in our cohort, which are not able to fold correctly and pass the quality control of the ER. In concordance, we found autosomal dominant familial neurohypophyseal diabetes insipidus in the 15 families studied.

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

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.

Genetics of Diabetes Insipidus

Diabetes insipidus is a disease characterized by polyuria and polydipsia due to inadequate release of arginine vasopressin from the posterior pituitary gland (neurohypophyseal diabetes insipidus) or due to arginine vasopressin insensitivity by the renal distal tubule, leading to a deficiency in tubular water reabsorption (nephrogenic diabetes insipidus). This article reviews the genetics of diabetes insipidus in the context of its diagnosis, clinical presentation, and therapy.

Amyloid-like aggregation of provasopressin in diabetes insipidus and secretory granule sorting

BACKGROUND

Aggregation of peptide hormone precursors in the trans-Golgi network is an essential process in the biogenesis of secretory granules in endocrine cells. It has recently been proposed that this aggregation corresponds to the formation of functional amyloids. Our previous finding that dominant mutations in provasopressin, which cause cell degeneration and diabetes insipidus, prevent native folding and produce fibrillar aggregates in the endoplasmic reticulum (ER) might thus reflect mislocalized amyloid formation by sequences that evolved to mediate granule sorting.

RESULTS

Here we identified two sequences responsible for fibrillar aggregation of mutant precursors in the ER: the N-terminal vasopressin nonapeptide and the C-terminal glycopeptide. To test their role in granule sorting, the glycopeptide was deleted and/or vasopressin mutated to inactivate ER aggregation while still permitting precursor folding and ER exit. These mutations strongly reduced sorting into granules and regulated secretion in endocrine AtT20 cells.

CONCLUSION

The same sequences - vasopressin and the glycopeptide - mediate physiological aggregation of the wild-type hormone precursor into secretory granules and the pathological fibrillar aggregation of disease mutants in the ER. These findings support the amyloid hypothesis for secretory granule biogenesis.

A missense mutation in the arginine-vasopressin neurophysin-II gene causes autosomal dominant neurohypophyseal diabetes insipidus in a Chinese family

BACKGROUND

Familial neurohypophyseal diabetes insipidus, an autosomal dominant disorder, is mostly caused by mutations in the genes that encode AVP or its intracellular binding protein, neurophysin-II. The mutations lead to aberrant preprohormone processing and progressive destruction of AVP-secreting cells, which gradually manifests a progressive polyuria and polydipsia during early childhood, and a disorder of water homeostasis.

OBJECTIVE

We characterized the clinical and biochemical features, and sequenced the AVP neurophysin-II(AVP-NPII) gene of the affected individuals with autosomal dominant neurohypophyseal diabetes insipidus(ADNDI)to determine whether this disease was genetically determined.

PATIENTS AND METHODS

We obtained the histories of eight affected and four unaffected family individuals. The diagnosis of ADNDI was established using a water deprivation test and exogenous AVP administration. For molecular analysis, genomic DNA was extracted and the AVP-NPII gene was amplified using polymerase chain reaction and sequenced.

RESULTS

The eight affected individuals showed different spectra of age of onsets (7-15 years) and urine volumes (132-253 ml/kg/24 h). All affected individuals responded to vasopressin administration, with a resolution of symptoms and an increase in urine osmolality by more than 50%. The characteristic hyperintense signal in the posterior pituitary on T1-weighted magnetic resonance imaging was absent in six family members and present in one. Sequencing analysis revealed a missense heterozygous mutation 1516G > T (Gly17Val) in exon 2 of the AVP-NPII gene among the ADNDI individuals.

CONCLUSIONS

We identified a missense mutation in the AVP-NPII gene and the same mutation showed different spectra of age of onsets and urine volumes in a new Chinese family with ADNDI. The mutation may provide a molecular basis for understanding the characteristics of NPII and add to our knowledge of the pathogenesis of ADNDI, which would allow the presymptomatic diagnosis of asymptomatic subjects.

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

The objective of this study is to identify the genetic defects in a Chinese family with autosomal dominant familial neurohypophyseal diabetes insipidus. Complete physical examination, fluid deprivation, and DDAVP tests were performed in three affected and three healthy members of the family. Genomic DNA was extracted from leukocytes of venous blood of these individuals for polymerase chain reaction amplification and direct sequencing of all three coding exons of arginine vasopressin-neurophysin II (AVP-NPII) gene. Seven members of this family were suspected to have symptomatic vasopressin-deficient diabetes insipidus. The water deprivation test in all the patients confirmed the diagnosis of vasopressin-deficient diabetes insipidus, with the pedigree demonstrating an autosomal dominant inheritance. Direct sequence analysis revealed a novel mutation (c.193T>A) and a synonymous mutation (c.192C>A) in the AVP-NPII gene. The missense mutation resulted in the substitution of cysteine by serine at a highly conserved codon 65 of exon 2 of the AVP-NPII gene in all affected individuals, but not in unaffected members. We concluded that a novel missense mutation in the AVP-NPII gene caused neurohypophyseal diabetes insipidus in this family, due to impaired neurophysin function as a carrier protein for AVP. The Cys65 is essential for NPII in the formation of a salt bridge with AVP. Presence of this mutation suggests that the portion of the neurophysin peptide encoded by this sequence is important for the normal expression of vasopressin.

A novel deletion partly removing the AVP gene causes autosomal recessive inheritance of early-onset neurohypophyseal diabetes insipidus

Familial neurohypophyseal diabetes insipidus (FNDI) typically presents with age-dependent penetrance and autosomal dominant inheritance caused by missense variations in one allele of the AVP gene encoding the arginine vasopressin (AVP) prohormone. We present the molecular genetic characteristics underlying an unusual form of FNDI occurring with very early onset and seemingly autosomal recessive inheritance. By DNA amplification and sequencing, we identified a novel variant allele of the AVP gene carrying a 10,396 base pair deletion involving the majority of the AVP gene as well as its regulatory sequences in the intergenic region between the AVP and the OXT gene, encoding the oxytocin prohormone. We found two chromosomes carrying the deletion in affected family members and one in unaffected family members suspected to transmit the deleted allele. Whole-genome array analysis confirmed the results and excluded the presence of any additional major pathogenic abnormalities. The deletion is predicted to abolish the transcription of the AVP gene, thus the fact that family members heterozygous for the deletion remain healthy argues, in general, against haploinsufficiency as the pathogenic mechanism FNDI. Accordingly, our data is strong support to the prevailing idea that dominant inheritance of FNDI is due to a dominant-negative effect exerted by variant AVP prohormone.