CONCOMITANT MUTATIONS IN INHERITED RETINAL DYSTROPHIES: Why the Reproductive and Therapeutic Counseling Should Be Addressed Cautiously

PURPOSE

To highlight the challenge of correct reproductive and therapeutic counseling in complex pedigrees with different inherited retinal dystrophies (IRD).

METHODS

Two hundred eight patients diagnosed with nonsyndromic IRD underwent full ophthalmologic examination and molecular analysis using targeted next-generation sequencing.

RESULTS

Five families (4%) carried mutations in more than one gene that contribute to different IRD. Family fRPN-NB had a dominant mutation in SNRNP200, which was present in nine affected individuals and four unaffected, and a mutation in RP2 among 11 family members. Family fRPN-142 carried a mutation in RPGR that cosegregated with the disease in all affected individuals. In addition, the proband also harbored two disease-causing mutations in the genes BEST1 and SNRNP200. Family fRPN-169 beared compound heterozygous mutations in USH2A and a dominant mutation in RP1. Genetic testing of fRPN-194 determined compound heterozygous mutations in CNGA3 and a dominant mutation in PRPF8 only in the proband. Finally, fRPN-219 carried compound heterozygous mutations in the genes ABCA4 and TYR.

CONCLUSION

These findings reinforce the complexity of IRD and underscore the need for the combination of high-throughput genetic testing and clinical characterization. Because of these features, the reproductive and therapeutic counseling for IRD must be approached with caution.

Usher Syndrome: Genetics of a Human Ciliopathy

Usher syndrome (USH) is an autosomal recessive syndromic ciliopathy characterized by sensorineural hearing loss, retinitis pigmentosa and, sometimes, vestibular dysfunction. There are three clinical types depending on the severity and age of onset of the symptoms; in addition, ten genes are reported to be causative of USH, and six more related to the disease. These genes encode proteins of a diverse nature, which interact and form a dynamic protein network called the “Usher interactome”. In the organ of Corti, the USH proteins are essential for the correct development and maintenance of the structure and cohesion of the stereocilia. In the retina, the USH protein network is principally located in the periciliary region of the photoreceptors, and plays an important role in the maintenance of the periciliary structure and the trafficking of molecules between the inner and the outer segments of photoreceptors. Even though some genes are clearly involved in the syndrome, others are controversial. Moreover, expression of some USH genes has been detected in other tissues, which could explain their involvement in additional mild comorbidities. In this paper, we review the genetics of Usher syndrome and the spectrum of mutations in USH genes. The aim is to identify possible mutation associations with the disease and provide an updated genotype–phenotype correlation.

Expanding the Clinical and Molecular Heterogeneity of Nonsyndromic Inherited Retinal Dystrophies

A cohort of 172 patients diagnosed clinically with nonsyndromic retinal dystrophies, from 110 families underwent full ophthalmologic examination, including retinal imaging, electrophysiology, and optical coherence tomography, when feasible. Molecular analysis was performed using targeted next-generation sequencing (NGS). Variants were filtered and prioritized according to the minimum allele frequency, and finally classified according to the American College of Medical Genetics and Genomics guidelines. Multiplex ligation-dependent probe amplification and array comparative genomic hybridization were performed to validate copy number variations identified by NGS. The diagnostic yield of this study was 62% of studied families. Thirty novel mutations were identified. The study found phenotypic intra- and interfamilial variability in families with mutations in C1QTNF5, CERKL, and PROM1; biallelic mutations in PDE6B in a unilateral retinitis pigmentosa patient; interocular asymmetry RP in 50% of the symptomatic RPGR-mutated females; the first case with possible digenism between CNGA1 and CNGB1; and a ROM1 duplication in two unrelated retinitis pigmentosa families. Ten unrelated cases were reclassified. This study highlights the clinical utility of targeted NGS for nonsyndromic inherited retinal dystrophy cases and the importance of full ophthalmologic examination, which allows new genotype-phenotype associations and expands the knowledge of this group of disorders. Identifying the cause of disease is essential to improve patient management, provide accurate genetic counseling, and take advantage of gene therapy-based treatments.

The importance of biochemical and genetic findings in the diagnosis of atypical Norrie disease

BACKGROUND

Norrie disease (ND) is a rare X-linked disorder characterized by bilateral congenital blindness. ND is caused by a mutation in the Norrie disease pseudoglioma (NDP) gene, which encodes a 133-amino acid protein called norrin. Intragenic deletions including NDP and adjacent genes have been identified in ND patients with a more severe neurologic phenotype. We report the biochemical, molecular, clinical and radiological features of two unrelated affected males with a deletion including NDP and MAO genes.

METHODS

Biochemical and genetic analyses were performed to understand the atypical phenotype and radiological findings. Biogenic amines in cerebrospinal fluid (CSF) were measured by high-performance liquid chromatography. The coding exons of NDP gene were amplified by polymerase chain reaction. Multiplex ligation-dependent probe amplification and chromosomal microarray were carried out on both affected males. Computed tomography and magnetic resonance imaging were performed on the two patients.

RESULTS

In one patient, the serotonin and catecholamine metabolite levels in CSF were virtually undetectable. In both patients, genetic studies revealed microdeletions in the Xp11.3 region, involving the NDP, MAOA and MAOB genes. Radiological examination demonstrated brain and cerebellar atrophy.

CONCLUSIONS

We suggest that alterations caused by MAO deficit may remain during the first years of life. Clinical phenotype, biochemical findings and neuroimaging can guide the genetic study in patients with atypical ND and help us to a better understanding of this disease.

Levels of regulatory T cells CD69(+)NKG2D(+)IL-10(+) are increased in patients with autoimmune thyroid disorders

Regulatory T (Treg) cells play an important role in the pathogenesis of autoimmune thyroid disorders (AITD). New subsets of CD4(+)CD69(+) and CD4(+)NKG2D(+) T lymphocytes that behave as regulatory cells have been recently reported. The role of these immunoregulatory lymphocytes has not been previously explored in AITD. We analyzed by multi-parametric flow cytometry different Treg cell subsets in peripheral blood from 32 patients with AITD and 19 controls, and in thyroid tissue from seven patients. The suppressive activity was measured by an assay of inhibition of lymphocyte activation. We found a significant increased percentage of CD4(+)CD69(+)IL-10(+), CD4(+)CD69(+)NKG2D(+), and CD4(+)CD69(+)IL-10(+)NKG2D(+) cells, in peripheral blood from GD patients compared to controls. The increase in CD4(+)CD69(+)IL-10(+) and CD4(+)CD69(+)IL-10(+)NKG2D(+) T cells was especially remarkable in patients with active Graves' ophthalmopathy (GO), and a significant positive correlation between GO activity and CD4(+)CD69(+)IL-10(+) or CD4(+)CD69(+)IL-10(+)NKG2D(+) cells was also found. In addition, these cells were increased in patients with a more severe and/or prolonged disease. Thyroid from AITD patients showed an increased proportion of CD69(+) regulatory T cells subpopulations compared to autologous peripheral blood. The presence of CD69(+), NKG2D(+), and IL-10(+) cells was confirmed by immunofluorescence microscopy. In vitro functional assays showed that CD69(+) Treg cells exerted an important suppressive effect on the activation of T effector cells in controls, but not in AITD patients. Our findings suggest that the levels of CD69(+) regulatory lymphocytes are increased in AITD patients, but they are apparently unable to down-modulate the autoimmune response and tissue damage.

Circulating Microvesicles Regulate Treg and Th17 Differentiation in Human Autoimmune Thyroid Disorders

BACKGROUND

Microvesicles (MVs) are emerging as important contributors to the development of inflammatory and autoimmune diseases. MVs can mediate immune modulation carrying genetic information, including microRNAs that can be transferred between cells.

DESIGN

We determined the plasma levels of annexin-V+ MVs derived from different immune cells and platelets in patients with autoimmune thyroid diseases (AITDs) and in healthy controls. T lymphocyte polarization assays were performed in the presence of MVs to evaluate their effect in T regulatory and T helper 17 cells differentiation. microRNA content into plasma MVs and their corresponding mRNA targets were evaluated by RT-PCR.

RESULTS

The percentage of platelet-derived MVs (CD41a+) was significantly increased in plasma samples from AITD patients compared with healthy controls. In contrast, patients with AITD showed a lower percentage of leukocyte and endothelial cell-derived MVs compared with controls. In addition, functional assays showed that MVs from AITD patients inhibited the in vitro differentiation of Foxp3+ T regulatory cells (11.35% vs 4.40%, P = .01) and induced the expression of interferon-γ by CD4+ lymphocytes (10.91% vs 13.99%, P = .01) as well as the differentiation of T helper 17 pathogenic (IL-17+interferon-γ+) cells (1.98% vs 5.13%, P = .03). Furthermore, in AITD patients, whereas miR-146a and miR-155 were increased in circulating MVs, their targets IL-8 and SMAD4 were decreased in peripheral blood mononuclear cells.

CONCLUSIONS

Our data indicate that circulating MVs seem to have a relevant role in the modulation of the inflammatory response observed in AITD.

Graves' disease is associated with a defective expression of the immune regulatory molecule galectin-9 in antigen-presenting dendritic cells

Introduction

Patients with autoimmune thyroid disease (AITD) show defects in their immune-regulatory mechanisms. Herein we assessed the expression and function of galectin-1 and galectin-9 (Gal-1, Gal-9) in dendritic cells (DCs) from patients with AITD.

Materials and Methods

Peripheral blood samples from 25 patients with Graves’ disease (GD), 11 Hashimoto’s thyroiditis (HT), and 24 healthy subjects were studied. Thyroid tissue samples from 44 patients with AITD and 22 patients with goiter were also analyzed. Expression and function of Gal-1 and Gal-9 was assessed by quantitative RT-PCR, immunofluorescence and flow cytometry.

Results

A diminished expression of Gal-9, but not of Gal-1, by peripheral blood DCs was observed in GD patients, mainly in those with Graves´ ophthalmopathy, and a significant negative association between disease severity and Gal-9 expression was detected. In addition, the mRNA levels of Gal-9 and its ligand TIM-3 were increased in thyroid tissue from AITD patients and its expression was associated with the levels of Th1/Th12/Th17 cytokines. Immunofluorescence studies proved that intrathyroidal Gal-9 expression was confined to DCs and macrophages. Finally, in vitro functional assays showed that exogenous Gal-9 had a suppressive effect on the release of Th1/Th2/Th17 cytokines by DC/lymphocyte autologous co-cultures from both AITD patients and healthy controls.

Conclusions

The altered pattern of expression of Gal-9 in peripheral blood DCs from GD patients, its correlation with disease severity as well as its ability to suppress cytokine release suggest that Gal-9 could be involved in the pathogenesis of AITD.

When an Analytical Interference Is a Useful Diagnostic Tool: Finding Monoclonal Gammopathies in Routine Analysis

BACKGROUND

The daily productivity of a clinical laboratory depends on the large number of interferences that affect analytical accuracy. Obviously, they have always been considered as a very important aspect to keep accuracy under control. Nevertheless, we wondered if this aspect would be beneficial. In this article, we propose a method for finding monoclonal gammopathies that are based on the fact that the presence of paraprotein in the sample may interfere with routine laboratory assays, specifically, with the quantification of uric acid and conjugated bilirubin.

METHODS

Over a 5-month period, we evaluated 18,278 sera samples of patients from primary care. None of them were suspected of having plasma cell dyscrasias (not observed hypercalcemia, renal failure, anemia, and/or lytic bone lesions). Although biochemical findings suggested paraprotein interference, we carried out serum capillary electrophoresis (CE) and quantification of immunoglobulins and serum-free light chains (SFLCs). We also confirmed the results obtained by performing the corresponding immunofixation electrophoresis (IFE). Flow cytometry analyses were conducted for immunophenotypic characterization of plasma cells from these patients.

RESULTS

The proposed detection method allowed us to identify eight patients with previously undiagnosed monoclonal gammopathy.

CONCLUSIONS

The results show that it is possible to use analytical interference for diagnostic purposes, and most importantly, almost all cases were identified at an early stage of the disease, when associated clinical manifestations were not yet observed.

Plasmacytoid dendritic cells in patients with autoimmune thyroid disease

BACKGROUND

Patients with autoimmune thyroid diseases (AITD) show defects in immunoregulatory mechanisms. Herein we assessed the expression of different regulatory receptors in circulating and thyroid dendritic cells (DCs).

DESIGN

Peripheral blood samples from 49 patients with Hashimoto's thyroiditis, 35 with Graves' disease, and 34 healthy subjects were studied. Clinical parameters included grades of goiter and ophthalmopathy, thyroid function, and antibody tests. Thyroid tissue samples from 10 AITD patients were also analyzed. Levels of DCs and their expression of different regulatory molecules (IDO, ILT2, ILT3, PSGL-1, PD-L1) were studied. In vitro interferon-α response by plasmacytoid DCs (pDCs) and tryptophan (Trp) metabolites were determined.

RESULTS

Significant low levels of pDCs, but not conventional DCs, were detected in the peripheral blood from AITD patients, mainly in those with severe disease. Furthermore, a diminished expression of ILT3, PSGL-1, and CD69 by peripheral blood pDCs from AITD patients was observed. An increased number of pDCs was found in thyroid tissue, showing a diminished expression of ILT3 and PSGL-1. A lower proportion of IDO+ pDCs, a significant increase in Trp levels, a decrease in the kyneruine/Trp ratio, and an increased in vitro interferon-α response were present in AITD patients. Finally, a significant correlation was found between the in vitro synthesis of IL-10 by stimulated T cells and expression of IDO by pDCs.

CONCLUSIONS

The diminished number of pDCs in the peripheral blood from AITD patients as well as their abnormal phenotype could contribute significantly to the pathogenesis.