A disorder clinically resembling cystic fibrosis caused by biallelic variants in the AGR2 gene

Purpose

We sought to describe a disorder clinically mimicking cystic fibrosis (CF) and to elucidate its genetic cause.

Methods

Exome/genome sequencing and human phenotype ontology data of nearly 40 000 patients from our Bio/Databank were analysed. RNA sequencing of samples from the nasal mucosa from patients, carriers and controls followed by transcriptome analysis was performed.

Results

We identified 13 patients from 9 families with a CF-like phenotype consisting of recurrent lower respiratory infections (13/13), failure to thrive (13/13) and chronic diarrhoea (8/13), with high morbidity and mortality. All patients had biallelic variants in AGR2, (1) two splice-site variants, (2) gene deletion and (3) three missense variants. We confirmed aberrant AGR2 transcripts caused by an intronic variant and complete absence of AGR2 transcripts caused by the large gene deletion, resulting in loss of function (LoF). Furthermore, transcriptome analysis identified significant downregulation of components of the mucociliary machinery (intraciliary transport, cilium organisation), as well as upregulation of immune processes.

Conclusion

We describe a previously unrecognised autosomal recessive disorder caused by AGR2 variants. AGR2-related disease should be considered as a differential diagnosis in patients presenting a CF-like phenotype. This has implications for the molecular diagnosis and management of these patients. AGR2 LoF is likely the disease mechanism, with consequent impairment of the mucociliary defence machinery. Future studies should aim to establish a better understanding of the disease pathophysiology and to identify potential drug targets.

Loss of C2orf69 defines a fatal autoinflammatory syndrome in humans and zebrafish that evokes a glycogen-storage-associated mitochondriopathy

Human C2orf69 is an evolutionarily conserved gene whose function is unknown. Here, we report eight unrelated families from which 20 children presented with a fatal syndrome consisting of severe autoinflammation and progredient leukoencephalopathy with recurrent seizures; 12 of these subjects, whose DNA was available, segregated homozygous loss-of-function C2orf69 variants. C2ORF69 bears homology to esterase enzymes, and orthologs can be found in most eukaryotic genomes, including that of unicellular phytoplankton. We found that endogenous C2ORF69 (1) is loosely bound to mitochondria, (2) affects mitochondrial membrane potential and oxidative respiration in cultured neurons, and (3) controls the levels of the glycogen branching enzyme 1 (GBE1) consistent with a glycogen-storage-associated mitochondriopathy. We show that CRISPR-Cas9-mediated inactivation of zebrafish C2orf69 results in lethality by 8 months of age due to spontaneous epileptic seizures, which is preceded by persistent brain inflammation. Collectively, our results delineate an autoinflammatory Mendelian disorder of C2orf69 deficiency that disrupts the development/homeostasis of the immune and central nervous systems.

Association of a point mutation (m.9176T>G) of the MT-ATP6 gene with Leigh syndrome: A case report

Leigh Syndrome (LS) is an uncommon progressive neurodegenerative mitochondrial disorder. The condition is characterized by progressive mental and developmental disabilities (psychomotor regression) and commonly brings about death within a few years of diagnosis, more often due to respiratory failure. In a small number of patients the disorder does not manifest until adulthood. The principal indications of Leigh syndrome found in early stages typically are diarrhea, vomiting, and difficulty swallowing (dysphagia), which disturbs eating. These problems usually result in powerlessness to develop and put on weight under the normal rate (failure to thrive). Serious movement and muscle problems are basic in Leigh syndrome. In this case report, we introduce the molecular and clinical features of a 19-year-old female as proband, and also, we study other members of the family consequently. The m.9176T>G heteroplasmic mutation in the MT-ATP6 gene was detected by high-resolution melt (HRM) and DNA sequencing techniques. Similarly, the m.9176T>G was heteroplasmic in the mother. In conclusion, this report in compliance with previous studies underlines the necessity of further research on prenatal distinguishing proof of the responsible mutations and avoidance of the disease in families with known cases.  

Interferon-induced retinopathy and its risk in patients with diabetes and hypertension undergoing treatment for chronic hepatitis C virus infection

BACKGROUND

Ocular complications are amongst many side-effects of interferon based therapy for hepatitis C virus (HCV) infection. Some suggest that diabetic and hypertensive patients are at increased risk of these complications.

AIM

To determine the frequency of ophthalmological complications related to interferon use.

METHODS

Retrospective analysis of patients undergoing HCV treatment with pegylated interferon alpha-2a, alpha-2b or consensus interferon plus ribavirin between 2005 and 2007. All patients underwent a baseline eye examination and any visual complaints during treatment prompted a repeat examination. Data recorded included HCV genotype, treatment duration, interferon type, pre-treatment and on treatment visual complaints, known ocular pathology, and retinal findings at baseline and at follow-up.

RESULTS

Of 183 patients, 29 (16%) had diabetes and 85 (46%) had hypertension. Seventy-one (38%) received interferon alpha-2a, 100 (55%) alpha-2b, and 12 (7%) consensus interferon. Seven (3.8%) had retinal changes on follow-up and treatment was discontinued in 3 (1.6%). Of seven with ocular changes two had hypertension and one had both hypertension and diabetes.

CONCLUSION

The incidence of symptomatic retinopathy in HCV patients undergoing interferon therapy appears low and treatment cessation is rarely needed. Furthermore, patients with hypertension and diabetes may not be at higher risk for interferon-induced retinopathy.

Review article: gastrointestinal amyloidosis - clinical features, diagnosis and therapy

BACKGROUND

Amyloidosis is one of the unusual diseases about which a physician may not think when it is affecting the patient. During the last three decades, there has been an enormous progress in the understanding of the chemical nature, classification, pathogenesis, clinical features, diagnostic measures and therapy of this disorder.

AIM

To provide an updated review of amyloidosis affecting the gastrointestinal tract.

METHODS

Review of current medical literature.

RESULTS

Amyloid proteins (irrespective of the type) can deposit in various parts of the gastrointestinal tract and liver resulting in symptoms of abdominal pain, dysmotility, diarrhoea, gastrointestinal bleeding, hepatomegaly and even portal hypertension with its associated complications. Definitive diagnosis can only be made by histological examination of the affected organ. Disease modifying treatment with high-dose chemotherapy followed by autologous stem-cell transplantation has shown promise. Liver transplantation is an option for a select group of patients.

CONCLUSIONS

Suspicion of gastrointestinal amyloidosis in patients without known history of amyloidosis is difficult, but should be considered in those older than 30 years with unexplained diarrhoea, weight loss, autonomic dysfunction, malabsorption or proteinuria. While most gastrointestinal complications are managed symptomatically, causal therapy is reserved for a select few from various subtypes of this disorder.