Identification of one novel causative mutation in exon 4 of WFS1 gene in two Italian siblings with classical DIDMOAD syndrome phenotype

Mutation analysis of pathogenic non-synonymous single nucleotide polymorphisms (nsSNPs) in WFS1 gene through computational approaches

A single base changes causing a change to the amino acid sequence of the encoded protein, which is defined as non-synonymous single nucleotide polymorphisms (nsSNPs). Many of the nsSNPs can cause disease, and these nsSNPs are considered as pathogenic mutations. In the study, the high-risk nsSNPs of WFS1 and their influence on the structure and function of wolframin protein were predicted by multiple bioinformatics software. We obtained 13 high-risk nsSNPs of WFS1. All the 13 high-risk nsSNPs are highly conserved residues with a conservative score of 9 or 8 and mostly may cause a decrease in protein stability. The high-risk nsSNPs have an important effect on not only amino acid size, charge and hydrophobicity, but also protein's spatial structure. Among these, 11 nsSNPs had been previously published or cited and 2 nsSNPs (G695S and E776K) had not been reported to date. The two novel variants increased or decreased hydrogen bonds. In conclusion, through different computational tools, it is presumed that the mechanism of pathogenic WFS1 nsSNPs should include the changes of physicochemical properties, significant structural changes and abnormal binding with functional partners. We accomplished the computational-based screening and analysis for deleterious nsSNPs in WFS1, which had important reference value and could contribute to further studies of the mechanism of WFS1 related disease. The computational analysis has many advantages, but the results should be identified by further experimental studies in vivo and in vitro.

Wolfram syndrome 1 in the Italian population: genotype-phenotype correlations

OBJECTIVES

We studied 45 patients with Wolfram syndrome 1 (WS1) to describe their clinical history and to search for possible genotype-phenotype correlations.

METHODS

Clinical criteria contributing to WS1 diagnosis were analyzed. The patients were classified into three genotypic classes according to type of detected mutations.

RESULTS

WS1 prevalence in Italy is 0.74/1,000,000. All four manifestations of DIDMOAD were found in 46.7% of patients. Differently combined WS1 clinical features were detected in 53.3% of patients. We found 35 WFS1 different mutations and a novel missense mutation, c.1523A>G. WS1 patients were homozygotes or compound heterozygotes for WFS1 mutations except for 2 heterozygote patients (4.5%). Each genotypic group exhibited a different age onset of DM, D, and DI but not of OA. Genotypic Group 2 patients manifested a lower number of clinical manifestations compared to Groups 1 and 3. Moreover, genotypic Group 1 patients tended to have a shorter survival time than the other groups. No differences were found regarding type of clinical pictures.

CONCLUSIONS

Our study suggested that molecular WFS1 typing is a useful tool for early assessment of clinical history, follow-up, and prognosis of WS1.

Wolfram syndrome, a rare neurodegenerative disease: from pathogenesis to future treatment perspectives

Background

Wolfram syndrome (WS), a rare genetic disorder, is considered the best prototype of endoplasmic reticulum (ER) diseases. Classical WS features are childhood-onset diabetes mellitus, optic atrophy, deafness, diabetes insipidus, neurological signs, and other abnormalities. Two causative genes (WFS1 and WFS2) have been identified. The transmission of the disease takes place in an autosomal recessive mode but autosomal dominant mutations responsible for WS-related disorders have been described. Prognosis is poor, death occurs at the median age of 39 years with a major cause represented by respiratory failure as a consequence of brain stem atrophy and neurodegeneration. The aim of this narrative review is to focus on etiology, pathogenesis and natural history of WS for an adequate patient management and for the discussion of future therapeutic interventions.

Main body

WS requires a multidisciplinary approach in order to be successfully treated. A prompt diagnosis decreases morbidity and mortality through prevention and treatment of complications. Being a monogenic pathology, WS represents a perfect model to study the mechanisms of ER stress and how this condition leads to cell death, in comparison with other prevalent diseases in which multiple factors interact to produce the disease manifestations. WS is also an important disease prototype to identify drugs and molecules associated with ER homeostasis. Evidence indicates that specific metabolic diseases (type 1 and type 2 diabetes), neurodegenerative diseases, atherosclerosis, inflammatory pathologies and also cancer are closely related to ER dysfunction.

Conclusions

Therapeutic strategies in WS are based on drug repurposing (i.e., investigation of approved drugs for novel therapeutic indications) with the aim to stop the progression of the disease by reducing the endoplasmic reticulum stress. An extensive understanding of WS from pathophysiology to therapy is fundamental and more studies are necessary to better manage this devastating disease and guarantee the patients a better quality of life and longer life expectancy.

Genetic and clinical aspects of Wolfram syndrome 1, a severe neurodegenerative disease

Wolfram syndrome 1 (WS1) is a rare autosomal recessive neurodegenerative disease characterized by diabetes insipidus, diabetes mellitus, optic atrophy, deafness, and other abnormalities. WS1 usually results in death before the age of 50 years. The pathogenesis of WS1 is ascribed to mutations of human WFS1 gene on chromosome 4p encoding a transmembrane protein called wolframin, which has physiological functions in membrane trafficking, secretion, processing, and/or regulation of ER calcium homeostasis. Different types of WFS1 mutations have been identified, and some of these have been associated with a dominant, severe type of WS. Mutations of CISD2 gene cause autosomal recessive Wolfram syndrome 2 (WS2) characterized by the absence of diabetes insipidus and psychiatric disorders, and by bleeding upper intestinal ulcer and defective platelet aggregation. Other WFS1-related disorders such as DFNA6/14/38 nonsyndromic low-frequency sensorineural hearing loss and Wolfram syndrome-like disease with autosomal dominant transmission have been described. WS1 is a devastating disease for the patients and their families. Thus, early diagnosis is imperative to enable proper prognostication, prevent complications, and reduce the transmission to further progeny. Although there is currently no effective therapy, potential new drugs have been introduced, attempting to improve the progression of this fatal disease.

No association between wolframin gene H611R polymorphism and mood disorders: evidence from 2,570 subjects

BACKGROUND

In the past few decades, a number of studies have investigated the association of the wolframin (WFS1) gene H611R polymorphism with mood disorders, but the findings are not always consistent.

AIMS

The objective of the present study is to assess the association between WFS1 gene H611R polymorphism and mood disorders by using a meta-analysis.

METHODS

A comprehensive literature search of PubMed, Excerpta Medica Database, Elsevier Science Direct and China National Knowledge Infrastructure databases was conducted to identify relevant articles, with the last report up to April 15, 2014. Pooled odds ratio (OR) with 95% confidence interval (CI) was estimated.

RESULTS

Seven studies including 1318 cases and 1252 controls were selected from potentially relevant articles. This meta-analysis showed that there was no significant association between WFS1 gene H611R polymorphism and mood disorders (R vs. H: OR = 0.93, 95% CI = 0.82-1.05, P = 0.22; HR+ RR vs. HH: OR = 0.98, 95% CI = 0.82-1.17, P = 0.80; RR vs. HH+ HR: OR = 0.84, 95% CI = 0.67-1.04, P = 0.11; RR vs. HH: OR = 0.86, 95% CI = 0.67-1.10, P = 0.24; HR vs. HH: OR = 1.03, 95% CI = 0.78-1.36, P = 0.83). In subgroup analyses by ethnicity, we did not detect any significant association of this polymorphism with mood disorders in Caucasian and Asian populations (P > 0.05). In subgroup analyses by types of mood disorders, we also did not detect any significant association of this polymorphism with bipolar disorder or major depressive disorder (P > 0.05).

CONCLUSIONS

The results of this meta-analysis suggest that there is no association between WFS1 gene H611R polymorphism and mood disorders.

Phenotypical and genotypical expression of Wolfram syndrome in 12 patients from a Sicilian district where this syndrome might not be so infrequent as generally expected

BACKGROUND

Since the original description, there have been only few epidemiological studies of Wolfram syndrome (WS).

AIM

Aims of the present paper are to ascertain WS prevalence and expression in a district of North-eastern Sicily, i.e. a geographic area where consanguineous unions are not very unusual.

MATERIALS AND METHODS

Prevalence rates of WS in the Messina district were calculated by taking into consideration both the total population (653,737) and the populations included within the 0-30 year age range (202,681). We estimated the relative prevalence of WS among patients with youth-onset insulin-dependent diabetes mellitus (DM) who are currently aged under 30 years (256).

RESULTS

Global WS prevalence in our district is 1:54,478, whereas prevalence among individuals under 30 is 1:16,890 and relative prevalence among patients with juvenile-onset insulin-dependent DM is 1:22.3. When compared with the patients with insulin-dependent DM of Messina district, WS patients did not exhibit significant differences in terms of biochemical features at DM onset, whereas age at DM diagnosis was significantly earlier in WS group.

CONCLUSIONS

(a) WS prevalence is not so infrequent as generally expected; (b) in our series, DM presented before 10 years in 11/12 patients and ten cases have already developed all the four peculiar manifestations of WS by 26 years; (c) 9/12 patients exhibited a homozygous frameshift/truncation mutation (Y454_L459del_fsX454), which is the one most frequently found also in patients from other Italian regions; (d) age at DM diagnosis was significantly earlier in WS group than in the patients with insulin-dependent DM of Messina district.