Factors Associated With Fatigue in People With Spinal Cord Injury: A Systematic Review and Meta-analysis.

OBJECTIVE: To investigate the association between fatigue and clinical and demographic variables in people with spinal cord injury (SCI). DATA SOURCES: Five databases (MEDLINE, Physiotherapy Evidence Database, Cochrane, Google Scholar, Cumulative Index to Nursing and Allied Health) were searched up to November 2021. STUDY SELECTION: Observational studies that reported the association between fatigue and clinical and demographic variables in English or Spanish were eligible. Reviews, qualitative research studies, and nonoriginal articles were excluded. Twenty-three of the 782 identified studies met the inclusion criteria for the meta-analysis. DATA EXTRACTION: Two researchers independently extracted the data. The strength of the association between each factor and fatigue was determined by the effect size. When the results of the effect size were expressed with different statistics, the correlation coefficient was the preferred estimation. The risk of bias was assessed using the Appraisal Tool for Cross-Sectional Studies and the Newcastle-Ottawa Scale. DATA SUMMARY: A pooled analysis of the associations between fatigue and 17 factors was performed. A direct association was found between fatigue and 9 factors (sorted by effect size): anxiety (r=0.57; 95% CI, 0.29-0.75), stress (r=0.54; 95% confidence interval [CI], 0.26-0.74), depression (r=0.47; 95% CI, 0.44-0.50), pain (r=0.34; 95% CI, 0.16-0.50), analgesic medication (r=0.32; 95% CI, 0.28-0.36), assistive devices (r=0.23; 95% CI, 0.17-0.29), lesion level (r=0.15; 95% CI, 0.07-0.23), incomplete SCI (r=0.13; 95% CI, 0.05-0.22), and medication (r=0.12; 95% CI, 0.01-0.23). An inverse association was found with 3 factors (sorted by effect size): self-efficacy (r=-0.63; 95% CI, -0.81 to -0.35), participation (r=-0.32; 95% CI, -0.58 to -0.001), and physical activity (r=-0.17; 95% CI, -0.28 to -0.05). No association was found with age, sex, educational level, time since injury, and spasticity. CONCLUSIONS: Several factors were associated with fatigue in people with SCI, with those related to mental health showing the strongest associations. These results should be interpreted with caution because of the high heterogeneity observed in some factors.

Differential Behavior of 25(OH)D and f25(OH)D3 in Patients with Morbid Obesity After Bariatric Surgery.

BACKGROUND: Total 25-OH-vitamin D (25(OH)D) levels are decreased in patients with obesity, but few data exist regarding free-vitamin D3 (f25(OH)D3) concentrations. We aimed to evaluate the effect of bariatric surgery on 25(OH)D and f25(OH)D3 in a cohort of patients with morbid obesity. METHODS: Twenty-four patients submitted to sleeve gastrectomy (SG) (mean age 48 years, body mass index (BMI) 48.16±10.73k/m2) were evaluated before and 1 year after surgery. Anthropometric data, parathormone (PTH), calcium, alkaline phosphatase, 25(OH)D, and f25(OH)D3 were recorded. RESULTS: 25(OH)D and f25(OH)D3 correlated well before and after SG. Baseline determinations did not correlate with BMI, but they inversely correlated with BMI 1 year after surgery (rs=-0.46, p=0.02 and rs=-0.60, p=0.002, respectively). Post-surgery % total body weight loss (%TBWL) was 27.4±13.8 %; f25(OH)D3 concentrations increased significantly (5.28±2.29 pg/mL vs 6.64±2.25 pg/mL; p=0.03), whereas 25(OH)D did not change. Patients who achieved a BMI <35 kg/m2 1 year after surgery had significantly higher concentrations of f25(OH)D3 (7.9±1 pg/mL vs 4.8±1.1, p<0.001) and 25(OH)D (30.9±9.4 ng/mL vs 22.3±13.4; p=0.03) compared to those who remained with BMI >35 kg/m2. CONCLUSION: There is a significant inverse relationship between BMI and both f25(OH)D3 and 25(OH)D 1 year after surgery. Only f25(OH)D3 concentrations increased 1 year after surgery, which could be explained by a greater f25(OH)D3 sequestration before SG in the adipose tissue, potentially due to the more liposoluble nature of f25(OH)D3 than the protein-bound form 25(OH)D.

Multicolor Imaging for the Detection of Inner Nuclear Layer Microcysts Secondary to Optic Nerve Atrophy.

ABSTRACT: Inner nuclear layer (INL) microcysts have been reported in diseases affecting the optic nerve. The new ocular imaging techniques detect minimal structural alterations at the macula and correlate these findings to different etiologies with less invasive procedures. The relationship between ganglion cells distribution at the macula and chiasmal nerve fibers enables the diagnosis and location of neurological lesions by new generation optical coherence tomography (SD-OCT) imaging devices. We report the evaluation of a patient with a history of optic nerve trauma and macular INL microcysts with multicolor SD-OCT technology that shows a pattern that localizes the lesion to the left optic nerve and proximal segment of the chiasm.

Measured free 25-hydroxyvitamin D in healthy children and relationship to total 25-hydroxyvitamin D, calculated free 25-hydroxyvitamin D and vitamin D binding protein.

BACKGROUND: vitamin D deficiency in children is still a global health problem. Measuring free 25-hydroxyvitamin D concentrations could provide a better estimate of the vitamin D status than total 25-hydroxyvitamin D (25(OH)D) levels. OBJECTIVE: To assess the relationship between measured free vitamin D (m-f25(OH)D) and calculated free 25(OH)D (c-f25(OH)D), total 25(OH)D, intact parathyroid hormone (iPTH) and other markers of phosphocalcic metabolism. To establish serum m-f25(OH)D concentrations corresponding to a total 25(OH)D > 50 nmol/L which is accepted as vitamin D-sufficiency status in children. DESIGN: Prospective cohort study. SETTING: January and February 2017 in a Mediterranean population. PATIENTS: healthy children. MEASUREMENTS: m-f25(OH)D and vitamin D binding protein (VDBP) by ELISA. Free 25(OH)D was calculated using the formula described by Bikle. RESULTS: m-f25(OH)D directly correlated with total 25(OH)D (r:0.804,p < .001), serum calcium (r:0.26,p:0.035), and c-f25(OH)D (r:0.553,p:0.016); and inversely with iPTH (r:-0.374, p:0.002), alkaline phosphatase (r:-0.28, p:0.026), and age (r:-0.289, p:0.018). Total 25(OH)D correlated with the same parameters as m-f25(OH)D except for serum calcium. However, c-f25(OH)D correlated only with total 25(OH)D and VDBP, both included in the calculation formula. Multiple regression analysis showed that m-f25(OH)D variations were independently explained by calcium (ß:0.156, p:0.026) and total 25(OH)D (ß:0.043, p < .001). The optimal m-f25(OH)D cut-off for discriminating between insufficient and sufficient total 25(OH)D was >9.8 pmol/L (Area Under Curve (AUC): 0.897 (95% confidence interval (CI): (0.798-0.958); p < .001; sensitivity:72.7% (95%CI: 49.8-89.3); specificity: 95.5% (95%CI: 84.5-99.4)). CONCLUSIONS: Directly measured free vitamin D correlated better with markers of phosphocalcic metabolism than total 25(OH)D and c-f25(OH)D in a population of healthy children.

Combining targeted panel-based resequencing and copy-number variation analysis for the diagnosis of inherited syndromic retinopathies and associated ciliopathies.

Inherited syndromic retinopathies are a highly heterogeneous group of diseases that involve retinal anomalies and systemic manifestations. They include retinal ciliopathies, other well-defined clinical syndromes presenting with retinal alterations and cases of non-specific multisystemic diseases. The heterogeneity of these conditions makes molecular and clinical characterization of patients challenging in daily clinical practice. We explored the capacity of targeted resequencing and copy-number variation analysis to improve diagnosis of a heterogeneous cohort of 47 patients mainly comprising atypical cases that did not clearly fit a specific clinical diagnosis. Thirty-three likely pathogenic variants were identified in 18 genes (ABCC6, ALMS1, BBS1, BBS2, BBS12, CEP41, CEP290, IFT172, IFT27, MKKS, MYO7A, OTX2, PDZD7, PEX1, RPGRIP1, USH2A, VPS13B, and WDPCP). Molecular findings and additional clinical reassessments made it possible to accurately characterize 14 probands (30% of the total). Notably, clinical refinement of complex phenotypes was achieved in 4 cases, including 2 de novo OTX2-related syndromes, a novel phenotypic association for the ciliary CEP41 gene, and the co-existence of biallelic USH2A variants and a Koolen-de-Vries syndrome-related 17q21.31 microdeletion. We demonstrate that combining next-generation sequencing and CNV analysis is a comprehensive and useful approach to unravel the extensive phenotypic and genotypic complexity of inherited syndromic retinopathies.

Mutations in SCAPER cause autosomal recessive retinitis pigmentosa with intellectual disability.

BACKGROUND: Retinitis pigmentosa (RP) is the most common form of inherited retinal dystrophy, with a worldwide prevalence of 1 in 4000 persons. While in most cases of RP, the disease is limited to the eye (non-syndromic), over 40 forms of syndromic RP have been described. OBJECTIVES: To identify the genetic basis for syndromic RP in three unrelated families from Israel and Spain. METHODS: Whole exome sequencing was conducted in one Israeli and two Spanish families segregating autosomal recessive RP with intellectual disability. Complete ophthalmic examination included best-corrected visual acuity, funduscopy, optical coherence tomography, fluorescein angiography, flash visual evoked potentials, and electroretinography. Reverse transcription (RT)-PCR and immunostaining were used to examine the spatial and temporal expression pattern of SCAPER. RESULTS: In all patients, biallelic SCAPER mutations were observed. Clinically, patients with SCAPER mutations show signs of typical RP. In addition, they have mild to moderate intellectual disability and attention-deficit/hyperactivity disorder. SCAPER was found to be ubiquitously expressed in a wide range of human tissues, including retina and brain. Furthermore, RT-PCR analysis revealed that in both mouse eye and brain, Scaper is expressed as early as embryonic day 14. In the mouse retina, SCAPER is located in multiple layers, including the retinal pigment epithelium, photoreceptor outer and inner segments, the inner plexiform layer and the ganglion cell layer. CONCLUSIONS: Deleterious SCAPER mutations were identified in four patients from three unrelated families of different ethnic backgrounds, thereby confirming the involvement of this gene in the aetiology of autosomal recessive syndromic RP.

Analysis of the PRPF31 Gene in Spanish Autosomal Dominant Retinitis Pigmentosa Patients: A Novel Genomic Rearrangement.

Purpose: The aim was to determine the prevalence of PRPF31 mutations in a cohort of Spanish autosomal dominant retinitis pigmentosa (adRP) families to deepen knowledge of the pathogenic mechanisms underlying the disease and to assess genotype-phenotype correlations. Methods: A cohort of 211 adRP patients was screened for variants in PRPF31 by using a combined strategy comprising next-generation sequencing approaches and copy-number variation (CNV) analysis. Quantitative RT-PCR and CNV analysis of the regulatory MSR1 element were also performed to assess PRPF31 gene expression. Phenotype was assessed by using ophthalmologic examination protocols. Results: Fifteen different causative mutations and genomic rearrangements were identified, revealing five novel mutations. Prevalence of PRPF31 mutations, genomic rearrangements, and lack of penetrance were 7.6%, 1.9%, and 66.7%, respectively. Interestingly, we identified a tandem duplication and a partial PRPF31 deletion in different affected individuals from the same family. PRPF31 gene expression was significantly decreased in symptomatic cases carrying either PRPF31 duplication or deletion as compared to controls. The 4 MSR1 allele in cis with the PRPF31 wild-type allele was apparently a protective factor. The mutated phenotype varied from no symptoms to typical retinitis pigmentosa with variable onset and course depending on the kind of mutation, with the duplication case the most severe. Conclusions: In view of the high genetic heterogeneity of PRPF31 mutations, the screening must include the entire gene, as well as CNV assays, to detect large rearrangements. This is the first report of a variable phenotype correlation as well as a gross duplication and deletion within the same family.

A Comprehensive Analysis of Choroideremia: From Genetic Characterization to Clinical Practice.

Choroideremia (CHM) is a rare X-linked disease leading to progressive retinal degeneration resulting in blindness. The disorder is caused by mutations in the CHM gene encoding REP-1 protein, an essential component of the Rab geranylgeranyltransferase (GGTase) complex. In the present study, we evaluated a multi-technique analysis algorithm to describe the mutational spectrum identified in a large cohort of cases and further correlate CHM variants with phenotypic characteristics and biochemical defects of choroideremia patients. Molecular genetic testing led to the characterization of 36 out of 45 unrelated CHM families (80%), allowing the clinical reclassification of four CHM families. Haplotype reconstruction showed independent origins for the recurrent p.Arg293* and p.Lys178Argfs*5 mutations, suggesting the presence of hotspots in CHM, as well as the identification of two different unrelated events involving exon 9 deletion. No certain genotype-phenotype correlation could be established. Furthermore, all the patients´ fibroblasts analyzed presented significantly increased levels of unprenylated Rabs proteins compared to control cells; however, this was not related to the genotype. This research demonstrates the major potential of the algorithm proposed for diagnosis. Our data enhance the importance of establish a differential diagnosis with other retinal dystrophies, supporting the idea of an underestimated prevalence of choroideremia. Moreover, they suggested that the severity of the disorder cannot be exclusively explained by the genotype.

Dominant Retinitis Pigmentosa, p.Gly56Arg Mutation in NR2E3: Phenotype in a Large Cohort of 24 Cases.

IMPORTANCE: This research is the single largest NR2E3 genotype-phenotype correlation study performed to date in autosomal dominant Retinitis Pigmentosa. OBJECTIVE: The aim of this study is to analyse the frequency of the p.Gly56Arg mutation in NR2E3 for the largest cohort of autosomal dominant Retinitis Pigmentosa patients to date and its associated phenotype. PATIENTS AND METHODS: A cohort of 201 unrelated Spanish families affected by autosomal dominant Retinitis Pigmentosa. The p.Gly56Arg mutation in the NR2E3 (NM_014249.2) gene was analysed in 201 families. In the 24 cases where the mutation had been detected, a haplotype analysis linked to the p.Gly56Arg families was performed, using four extragenic polymorphic markers D15S967, D15S1050, D15S204 and D15S188. Phenotype study included presence and age of onset of night blindness, visual field loss and cataracts; and an ophthalmoscopic examination after pupillary dilation and electroretinogram for the 24 cases. RESULTS: Seven of the 201 analyzed families were positive for the p.Gly56Arg, leading to a prevalence of 3.5%. Clinical data were available for 24 subjects. Night blindness was the first noticeable symptom (mean 15.9 years). Visual field loss onset was variable (23.3 ± 11.9 years). Loss of visual acuity appeared late in the disease´s evolution. Most of the patients with cataracts (50%) presented it from the third decade of life. Fundus changes showed inter and intrafamiliar variability, but most of the patients showed typical RP changes and it was common to find macular affectation (47.4%). Electroretinogram was impaired from the beginning of the disease. Two families shared a common haplotype. Additionally, all patients shared a 104Kb region between D15S1050 and the NR2E3 gene. CONCLUSIONS: This study highlights the importance of p.Gly56Arg in the NR2E3 gene as a common mutation associated with adRP, and provides new clues to its phenotype, which can allow for a better clinical management and genetic counselling of patients and their families.

Identification of two novel mutations in CDHR1 in consanguineous Spanish families with autosomal recessive retinal dystrophy.

Inherited retinal dystrophies present extensive phenotypic and genetic heterogeneity, posing a challenge for patients' molecular and clinical diagnoses. In this study, we wanted to clinically characterize and investigate the molecular etiology of an atypical form of autosomal recessive retinal dystrophy in two consanguineous Spanish families. Affected members of the respective families exhibited an array of clinical features including reduced visual acuity, photophobia, defective color vision, reduced or absent ERG responses, macular atrophy and pigmentary deposits in the peripheral retina. Genetic investigation included autozygosity mapping coupled with exome sequencing in the first family, whereas autozygome-guided candidate gene screening was performed by means of Sanger DNA sequencing in the second family. Our approach revealed nucleotide changes in CDHR1; a homozygous missense variant (c.1720C>G, p.P574A) and a homozygous single base transition (c.1485+2T>C) affecting the canonical 5' splice site of intron 13, respectively. Both changes co-segregated with the disease and were absent among cohorts of unrelated control individuals. To date, only five mutations in CDHR1 have been identified, all resulting in premature stop codons leading to mRNA nonsense mediated decay. Our work reports two previously unidentified homozygous mutations in CDHR1 further expanding the mutational spectrum of this gene.

Application of Whole Exome Sequencing in Six Families with an Initial Diagnosis of Autosomal Dominant Retinitis Pigmentosa: Lessons Learned.

This study aimed to identify the genetics underlying dominant forms of inherited retinal dystrophies using whole exome sequencing (WES) in six families extensively screened for known mutations or genes. Thirty-eight individuals were subjected to WES. Causative variants were searched among single nucleotide variants (SNVs) and insertion/deletion variants (indels) and whenever no potential candidate emerged, copy number variant (CNV) analysis was performed. Variants or regions harboring a candidate variant were prioritized and segregation of the variant with the disease was further assessed using Sanger sequencing in case of SNVs and indels, and quantitative PCR (qPCR) for CNVs. SNV and indel analysis led to the identification of a previously reported mutation in PRPH2. Two additional mutations linked to different forms of retinal dystrophies were identified in two families: a known frameshift deletion in RPGR, a gene responsible for X-linked retinitis pigmentosa and p.Ser163Arg in C1QTNF5 associated with Late-Onset Retinal Degeneration. A novel heterozygous deletion spanning the entire region of PRPF31 was also identified in the affected members of a fourth family, which was confirmed with qPCR. This study allowed the identification of the genetic cause of the retinal dystrophy and the establishment of a correct diagnosis in four families, including a large heterozygous deletion in PRPF31, typically considered one of the pitfalls of this method. Since all findings in this study are restricted to known genes, we propose that targeted sequencing using gene-panel is an optimal first approach for the genetic screening and that once known genetic causes are ruled out, WES might be used to uncover new genes involved in inherited retinal dystrophies.

Whole-exome sequencing reveals ZNF408 as a new gene associated with autosomal recessive retinitis pigmentosa with vitreal alterations.

Retinitis pigmentosa (RP) is a group of progressive inherited retinal dystrophies that cause visual impairment as a result of photoreceptor cell death. RP is heterogeneous, both clinically and genetically making difficult to establish precise genotype-phenotype correlations. In a Spanish family with autosomal recessive RP (arRP), homozygosity mapping and whole-exome sequencing led to the identification of a homozygous mutation (c.358_359delGT; p.Ala122Leufs*2) in the ZNF408 gene. A screening performed in 217 additional unrelated families revealed another homozygous mutation (c.1621C>T; p.Arg541Cys) in an isolated RP case. ZNF408 encodes a transcription factor that harbors 10 predicted C2H2-type fingers thought to be implicated in DNA binding. To elucidate the ZNF408 role in the retina and the pathogenesis of these mutations we have performed different functional studies. By immunohistochemical analysis in healthy human retina, we identified that ZNF408 is expressed in both cone and rod photoreceptors, in a specific type of amacrine and ganglion cells, and in retinal blood vessels. ZNF408 revealed a cytoplasmic localization and a nuclear distribution in areas corresponding with the euchromatin fraction. Immunolocalization studies showed a partial mislocalization of the p.Arg541Cys mutant protein retaining part of the WT protein in the cytoplasm. Our study demonstrates that ZNF408, previously associated with Familial Exudative Vitreoretinopathy (FEVR), is a new gene causing arRP with vitreous condensations supporting the evidence that this protein plays additional functions into the human retina.

Targeted Next-Generation Sequencing Improves the Diagnosis of Autosomal Dominant Retinitis Pigmentosa in Spanish Patients.

PURPOSE: Next-generation sequencing (NGS) has been demonstrated to be an effective strategy for the detection of mutations in retinal dystrophies, a group of inherited diseases that are highly heterogeneous. Therefore, the aim of this study is the application of an NGS-based approach in a Spanish cohort of autosomal dominant retinitis pigmentosa (RP) patients to find out causative mutations. METHODS: Index cases of 59 Spanish families with initial diagnosis of autosomal dominant RP and unsuccessfully studied for mutations in the most common RP causal genes, were selected for application of a NGS-based approach with a custom panel for 73 genes related to retinal dystrophies. Candidate variants were select based on frequency, pathogenicity, inherited model, and phenotype. Subsequently, confirmation by Sanger sequencing, cosegregation analysis, and population studies, was applied for determining the implication of those variants in the pathology. RESULTS: Overall 31 candidate variants were selected. From them, 17 variants were considered as mutations causative of the disease, 64% (11/17) of them were novel and 36% (6/17) were known RP-related mutations. Therefore, applying this technology16 families were characterized rendering a mutation detection rate of 27% (16/59). Of them, 5% (3/59) of cases displayed mutations in recessive or X-linked genes (ABCA4, RPGR, and RP2) allowing a genetic and clinical reclassification of those families. Furthermore, seven novel variants with uncertain significance and seven novel variants probably not causative of disease were also found. CONCLUSIONS: This NGS strategy is a fast, effective, and reliable tool to detect known and novel mutations in autosomal dominant RP patients allowing genetic reclassification in some cases and increasing the knowledge of pathogenesis in retinal dystrophies.

Prevalence of Rhodopsin mutations in autosomal dominant Retinitis Pigmentosa in Spain: clinical and analytical review in 200 families.

PURPOSE: We aimed to determine the prevalence of mutations in the RHO gene in Spanish families with autosomal dominant Retinitis Pigmentosa (adRP), to assess genotype-phenotype correlations and to establish an accurate diagnostic algorithm after 23 years of data collection. PATIENTS AND METHODS: Two hundred patients were analysed through a combination of denaturing gradient gel electrophoresis, single-strand conformation polymorphism, genotyping microarray and Sanger sequencing of the RHO gene. RESULTS: Overall, 42 of 200 Spanish adRP families were mutated for RHO (21.0%). Twenty-seven different RHO mutations were detected; seven of them were novel. A genotype-phenotype correlation was established with clinical data from 107 patients. The most prevalent p.Pro347Leu mutation, responsible for 4.5% (9/200) of all mutated adRP families, was associated with a phenotype of early onset and severe course diffuse RP. CONCLUSIONS: This retrospective study provides a wide spectrum of mutations in the RHO gene in Spanish patients with adRP. Also, the prevalence of mutations is similar to that reported in European population. Genotyping microarray followed by RHO sequencing is proposed as a first step in molecular diagnosis of adRP Spanish families. An increasing understanding of causal RHO alleles in adRP facilitates disease diagnosis and prognosis, especially for the prevalent p.Pro347Leu mutation.

New mutations in the RAB28 gene in 2 Spanish families with cone-rod dystrophy.

IMPORTANCE: The families evaluated in this study represent the second report of cone-rod dystrophy (CRD) cases caused by mutations in RAB28, a recently discovered gene associated with CRD. OBJECTIVE: To determine the disease-causing gene in 2 families of Spanish descent presenting with CRD who do not have ABCA4 mutations. DESIGN, SETTING, AND PARTICIPANTS: Molecular genetics and observational case studies of 2 families, each with 1 affected proband with CRD and 3 or 5 unaffected family members. The affected individual from each family received a complete ophthalmic examination including assessment of refractive errors and best-corrected visual acuity, biomicroscopy, color fundus photography, electroretinography analysis, and visual-evoked potential analysis. After complete sequencing of the ABCA4 gene with negative results, the screening for disease-causing mutations was performed by whole-exome sequencing. Possible disease-associated variants were determined by filtering based on minor allele frequency, predicted pathogenicity, and segregation analysis in all family members. MAIN OUTCOMES AND MEASURES: The appearance of the macula was evaluated by clinical examination, fundus photography, and fundus autofluorescence imaging, and visual function was assessed by electroretinography. Disease-causing mutations were assessed by sequence analyses. RESULTS: Ophthalmologic findings included markedly reduced visual acuity, bull's eye maculopathy, foveal hyperpigmentation, peripapillary atrophy, dyschromatopsia, extinguished photopic responses, and reduced scotopic responses observed on electroretinography consistent with the CRD phenotype often associated with ABCA4 mutations. Although no ABCA4 mutations were detected in either patient, whole-exome sequencing analysis identified 2 new homozygous mutations in the recently described RAB28 gene, the c.172 + 1G>C splice site variant in IVS2 and the missense c.T651G:p.C217W substitution. Both variants were determined as deleterious by predictive programs and were segregated with the disease in both families. Sequencing of 107 additional patients of Spanish descent with CRD did not reveal other cases with RAB28 mutations. CONCLUSIONS AND RELEVANCE: Deleterious mutations in RAB28 result in a classic CRD phenotype and are an infrequent cause of CRD in the Spanish population.

Clinical aspects of Usher syndrome and the USH2A gene in a cohort of 433 patients.

IMPORTANCE: A new statistical approach is needed to describe the clinical differences between type I and type II Usher syndrome and between the 2 most frequent mutations in the USH2A gene. OBJECTIVES: To describe the primary phenotypic characteristics and differences between type I and type II Usher syndrome and to establish a phenotype-genotype correlation for the 2 most frequent mutations in the USH2A gene. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study at a genetics department, in which clinical evaluations were performed for 433 patients (297 unrelated families) who were classified as having type I, II, III, atypical, or unclassified Usher syndrome according to their clinical history, pedigree data, results from ophthalmological studies, and audiological, neurophysiological, and vestibular test results. Molecular studies were performed for 304 patients (256 unrelated families). The Mann-Whitney U test or the χ2 test was used for calculating the differences between mean values for the analyzed parameters. MAIN OUTCOMES AND MEASURES: Age at diagnosis; age at onset of night blindness, visual field loss, visual acuity loss, and cataracts; and severity and age at diagnosis of hearing loss. RESULTS: The comparison between patients with type I Usher syndrome and those with type II Usher syndrome revealed P < .001 for most items analyzed. The most frequent mutations in the USH2A gene were the p.Glu767Serfs*21 and p.Cys759Phe mutations, with an allelic frequency of 23.2% (63 of 272 alleles) and 8.1% (22 of 272 alleles), respectively. The phenotypic analysis for patients carrying p.Cys759Phe showed P < .001 for most items analyzed when compared with patients carrying p.Glu767Serfs*21 and when compared with patients carrying other mutations in the USH2A gene. None of the p.Cys759Phe patients exhibited a severe hearing loss phenotype, and more than 60% had only mild hearing loss. Most patients carrying the p.Glu767Serfs*21 mutation (72.1%) were moderately deaf. CONCLUSIONS AND RELEVANCE: Our study presents the clinical differences between type I and type II Usher syndrome and between the 2 most frequent mutations in the USH2A gene. Detailed genotype-phenotype correlations, as presented in our study, allow for a better correlation of clinical signs with a known genotype and can improve the clinical management, genetic counseling, and risk assessment of patients with Usher syndrome because an estimated prognosis of their disease can be made.

Expanding the phenotype of PRPS1 syndromes in females: neuropathy, hearing loss and retinopathy.

BACKGROUND: Phosphoribosyl pyrophosphate synthetase (PRS) I deficiency is a rare medical condition caused by missense mutations in PRPS1 that lead to three different phenotypes: Arts Syndrome (MIM 301835), X-linked Charcot-Marie-Tooth (CMTX5, MIM 311070) or X-linked non-syndromic sensorineural deafness (DFN2, MIM 304500). All three are X-linked recessively inherited and males affected display variable degree of central and peripheral neuropathy. We applied whole exome sequencing to a three-generation family with optic atrophy followed by retinitis pigmentosa (RP) in all three cases, and ataxia, progressive peripheral neuropathy and hearing loss with variable presentation. METHODS: Whole exome sequencing was performed in two affecteds and one unaffected member of the family. Sanger sequencing was used to validate and segregate the 12 candidate mutations in the family and to confirm the absence of the novel variant in PRPS1 in 191 controls. The pathogenic role of the novel mutation in PRPS1 was assessed in silico and confirmed by enzymatic determination of PRS activity, mRNA expression and sequencing, and X-chromosome inactivation. RESULTS: A novel missense mutation was identified in PRPS1 in the affected females. Age of onset, presentation and severity of the phenotype are highly variable in the family: both the proband and her mother have neurological and ophthalmological symptoms, whereas the phenotype of the affected sister is milder and currently confined to the eye. Moreover, only the proband displayed a complete lack of expression of the wild type allele in leukocytes that seems to correlate with the degree of PRS deficiency and the severity of the phenotype. Interestingly, optic atrophy and RP are the only common manifestations to all three females and the only phenotype correlating with the degree of enzyme deficiency. CONCLUSIONS: These results are in line with recent evidence of the existence of intermediate phenotypes in PRS-I deficiency syndromes and demonstrate that females can exhibit a disease phenotype as severe and complex as their male counterparts.

Contribution of mutation load to the intrafamilial genetic heterogeneity in a large cohort of Spanish retinal dystrophies families.

PURPOSE: The aim of this study was to deepen our knowledge on the basis of intrafamilial genetic heterogeneity of inherited retinal dystrophies (RD) to further discern the contribution of individual alleles to the pathology. METHODS: Families with intrafamilial locus and/or allelic heterogeneity were selected from a cohort of 873 characterized of 2468 unrelated RD families. Clinical examination included visual field assessments, electrophysiology, fundus examination, and audiogram. Molecular characterization was performed using a combination of different methods: genotyping microarray, single strand conformational polymorphism (SSCP), denaturing high pressure liquid chromatography (dHPLC), high resolution melt (HRM), multiplex ligation-dependent probe amplification (MLPA), Sanger sequencing, whole-genome homozygosity mapping, and next-generation sequencing (NGS). RESULTS: Overall, intrafamilial genetic heterogeneity was encountered in a total of 8 pedigrees. There were 5 of 873 families (~0.6%) with causative mutations in more than one gene (locus heterogeneity), involving the genes: (1) USH2A, RDH12, and TULP1; (2) PDE6B and a new candidate gene; (3) CERKL and CRB1; (4) BBS1 and C2orf71; and (5) ABCA4 and CRB1. Typically, in these cases, each mutated gene was associated with different phenotypes. In the 3 other families (~0.35%), different mutations in the same gene (allelic heterogeneity) were found, including the frequent RD genes ABCA4 and CRB1. CONCLUSIONS: This systematic research estimates that the frequency of overall mutation load promoting RD intrafamilial heterogeneity in our cohort of Spanish families is almost 1%. The identification of the genetic mechanisms underlying RD locus and allelic heterogeneity is essential to discriminate the real contribution of the monoallelic mutations to the disease, especially in the NGS era. Moreover, it is decisive to provide an accurate genetic counseling and in disease treatment.

Exome sequencing extends the phenotypic spectrum for ABHD12 mutations: from syndromic to nonsyndromic retinal degeneration.

OBJECTIVE: To identify the genetic causes underlying autosomal recessive retinitis pigmentosa (arRP) and to describe the associated phenotype. DESIGN: Case series. PARTICIPANTS: Three hundred forty-seven unrelated families affected by arRP and 33 unrelated families affected by retinitis pigmentosa (RP) plus noncongenital and progressive hearing loss, ataxia, or both, respectively. METHODS: A whole exome sequencing (WES) analysis was performed in 2 families segregating arRP. A mutational screening was performed in 378 additional unrelated families for the exon-intron boundaries of the ABHD12 gene. To establish a genotype-phenotype correlation, individuals who were homozygous or compound heterozygotes of mutations in ABHD12 underwent exhaustive clinical examinations by ophthalmologists, neurologists, and otologists. MAIN OUTCOME MEASURES: DNA sequence variants, best-corrected visual acuity, visual field assessments, electroretinogram responses, magnetic resonance imaging, and audiography. RESULTS: After a WES analysis, we identified 4 new mutations (p.Arg107Glufs*8, p.Trp159*, p.Arg186Pro, and p.Thr202Ile) in ABHD12 in 2 families (RP-1292 and W08-1833) previously diagnosed with nonsyndromic arRP, which cosegregated with the disease among the family members. Another homozygous mutation (p.His372Gln) was detected in 1 affected individual (RP-1487) from a cohort of 378 unrelated arRP and syndromic RP patients. After exhaustive clinical examinations by neurologists and otologists, the 4 affected members of the RP-1292 had no polyneuropathy or ataxia, and the sensorineural hearing loss and cataract were attributed to age or the normal course of the RP, whereas the affected members of the families W08-1833 and RP-1487 showed clearly symptoms associated with polyneuropathy, hearing loss, cerebellar ataxia, RP, and early-onset cataract (PHARC) syndrome. CONCLUSIONS: Null mutations in the ABHD12 gene lead to PHARC syndrome, a neurodegenerative disease including polyneuropathy, hearing loss, cerebellar ataxia, RP, and early-onset cataract. Our study allowed us to report 5 new mutations in ABHD12. This is the first time missense mutations have been described for this gene. Furthermore, these findings are expanding the spectrum of phenotypes associated with ABHD12 mutations ranging from PHARC syndrome to a nonsyndromic form of retinal degeneration.