DEXAMETHASONE IMPLANT VERSUS TOPICAL CARBONIC ANHYDRASE INHIBITORS IN PATIENTS WITH BILATERAL RETINITIS PIGMENTOSA-RELATED CYSTOID MACULAR EDEMA: A Prospective, Paired-Eye Pilot Study.

PURPOSE: To compare within-subject efficacy and safety of intravitreal dexamethasone implant and topical carbonic anhydrase inhibitors in the treatment of retinitis pigmentosa-related cystoid macular edema. METHODS: Patients with bilateral retinitis pigmentosa-related cystoid macular edema were treated with intravitreal dexamethasone implant in one eye and topical carbonic anhydrase inhibitors in the contralateral eye. The primary endpoint was a change in central macular thickness. Secondary endpoints were changes in best-corrected visual acuity and microperimetric central retinal sensitivity. Intraocular pressure and other ocular complications were evaluated for safety assessment. RESULTS: Nine patients were recruited for this 12-month follow-up study. Central macular thickness was significantly lower in intravitreal dexamethasone implant-treated eyes than in topical carbonic anhydrase inhibitors-treated eyes at Months 1 and 7, whereas mean best-corrected visual acuity was better in eyes treated with topical carbonic anhydrase inhibitors at Month 12 (borderline significant P = 0.0510). There was no difference in microperimetric sensitivity between the two treatments. Three patients developed ocular hypertension after intravitreal dexamethasone implant. Intravitreal dexamethasone implant showed an effect on the contralateral eye in five of nine patients. CONCLUSION: Intravitreal dexamethasone implant was more effective than topical carbonic anhydrase inhibitors in reducing retinitis pigmentosa-related cystoid macular edema 1 month after treatment. Corticosteroids can play a key role in the management of retinitis pigmentosa-related cystoid macular edema; however, their routes, timing, and modes of administration should be further explored.

Genotypic and Phenotypic Characterization of a Cohort of Patients Affected by Rod Cyclic Nucleotide Channel-Associated Retinitis Pigmentosa.

INTRODUCTION: Retinitis pigmentosa (RP), a heterogeneous inherited retinal disorder causing gradual vision loss, affects over 1 million people worldwide. Pathogenic variants in CNGA1 and CNGB1 genes, respectively, accounting for 1% and 4% of cases, impact the cyclic nucleotide-gated channel in rod photoreceptor cells. The aim of this study was to describe and compare genotypic and clinical characteristics of a cohort of patients with CNGA1- or CNGB1-related RP and to explore potential genotype-phenotype correlations. METHODS: The following data from patients with CNGA1- or CNGB1-related RP, followed in five Italian inherited retinal degenerations services, were retrospectively collected: genetic variants in CNGA1 and CNGB1, best-corrected visual acuity (BCVA), ellipsoid zone (EZ) width, fundus photographs, and short-wavelength fundus autofluorescence (SW-AF) images. Comparisons and correlation analyses were performed by first dividing the cohort in two groups according to the gene responsible for the disease (CNGA1 and CNGB1 groups). In parallel, the whole cohort of RP patients was divided into two other groups, according to the expected impact of the variants at protein level (low and high group). RESULTS: In total, 29 patients were recruited, 11 with CNGA1- and 18 with CNGB1-related RP. In both CNGA1 and CNGB1, 5 novel variants in CNGA1 and 5 in CNGB1 were found. BCVA was comparable between CNGA1 and CNGB1 groups, as well as between low and high groups. CNGA1 group had a larger mean EZ width compared to CNGB1 group, albeit not statistically significant, while EZ width did not differ between low and high groups A statistically significant correlation between EZ width and BCVA as well as between EZ width and age were observed in the whole cohort of RP patients. Fundus photographs of all patients in the cohort showed classic RP pattern, and in SW-AF images an hyperautofluorescent ring was observed in 14/21 patients. CONCLUSION: Rod CNG channel-associated RP was demonstrated to be a slowly progressive disease in both CNGA1- and CNGB1-related forms, making it an ideal candidate for gene augmentation therapies.

RP1 Dominant p.Ser740* Pathogenic Variant in 20 Knowingly Unrelated Families Affected by Rod-Cone Dystrophy: Potential Founder Effect in Western Sicily.

Background and Objectives. Retinitis pigmentosa (RP) is the most common inherited rod-cone dystrophy (RCD), resulting in nyctalopia, progressive visual field, and visual acuity decay in the late stages. The autosomal dominant form (ADRP) accounts for about 20% of RPs. Among the over 30 genes found to date related to ADRP, RP1 pathogenic variants have been identified in 5-10% of cases. In a cohort of RCD patients from the Palermo province on the island of Sicily, we identified a prevalent nonsense variant in RP1, which was associated with ADRP. The objective of our study was to analyse the clinical and molecular data of this patient cohort and to evaluate the potential presence of a founder effect. Materials and Methods. From 2005 to January 2023, 84 probands originating from Western Sicily (Italy) with a diagnosis of RCD or RP and their relatives underwent deep phenotyping, which was performed in various Italian clinical institutions. Molecular characterisation of patients and familial segregation of pathogenic variants were carried out in different laboratories using Sanger and/or next-generation sequencing (NGS). Results. Among 84 probands with RCD/RP, we found 28 heterozygotes for the RP1 variant c.2219C>G, p.Ser740* ((NM_006269.2)*, which was therefore significantly prevalent in this patient cohort. After a careful interview process, we ascertained that some of these patients shared the same pedigree. Therefore, we were ultimately able to define 20 independent family groups with no traceable consanguinity. Lastly, analysis of clinical data showed, in our patients, that the p.Ser740* nonsense variant was often associated with a late-onset and relatively mild phenotype. Conclusions. The high prevalence of the p.Ser740* variant in ADRP patients from Western Sicily suggests the presence of a founder effect, which has useful implications for the molecular diagnosis of RCD in patients coming from this Italian region. This variant can be primarily searched for in RP-affected subjects displaying compatible modes of transmission and phenotypes, with an advantage in terms of the required costs and time for analysis. Moreover, given its high prevalence, the RP1 p.Ser740* variant could represent a potential candidate for the development of therapeutic strategies based on gene editing or translational read-through therapy for suppression of nonsense variants.

Optimization of long-range PCR protocol to prepare filaggrin exon 3 libraries for PacBio long-read sequencing.

BACKGROUND: The filaggrin (FLG) protein, encoded by the FLG gene, is an intermediate filament-associated protein that plays a crucial role in the terminal stages of human epidermal differentiation. Loss-of-function mutations in the FLG exon 3 have been associated with skin diseases. The identification of causative mutations is challenging, due to the high sequence homology within its exon 3 (12,753 bp), which includes 10 to 12 filaggrin tandem repeats. With this study we aimed to obtain the whole FLG exon 3 sequence through PacBio technology, once 13-kb amplicons have been generated. METHODS AND RESULTS: For the preparation of SMRTbell libraries to be sequenced using PacBio technology, we focused on optimizing a 2-step long-range PCR protocol to generate 13-kb amplicons covering the whole FLG exon 3 sequence. The performance of three long-range DNA polymerases was assessed in an attempt to improve the PCR conditions required for the enzymes to function properly. We focused on optimization of the input template DNA concentration and thermocycling parameters to correctly amplify the entire FLG exon 3 sequence, minimizing non-specific amplification. CONCLUSIONS: Taken together, our findings suggested that the PrimeSTAR protocol is suitable for producing the amplicons of the 13-kb FLG whole exon 3 to prepare SMRTbell libraries. We suggest that sequencing the generated amplicons may be useful for identifying LoF variants that are causative of the patients' disorders.

Genetic Analysis of Patients with Congenital Hypogonadotropic Hypogonadism: A Case Series.

Congenital hypogonadotropic hypogonadism (cHH)/Kallmann syndrome (KS) is a rare genetic disorder with variable penetrance and a complex inheritance pattern. Consequently, it does not always follow Mendelian laws. More recently, digenic and oligogenic transmission has been recognized in 1.5-15% of cases. We report the results of a clinical and genetic investigation of five unrelated patients with cHH/KS analyzed using a customized gene panel. Patients were diagnosed according to the clinical, hormonal, and radiological criteria of the European Consensus Statement. DNA was analyzed using next-generation sequencing with a customized panel that included 31 genes. When available, first-degree relatives of the probands were also analyzed to assess genotype-phenotype segregation. The consequences of the identified variants on gene function were evaluated by analyzing the conservation of amino acids across species and by using molecular modeling. We found one new pathogenic variant of the CHD7 gene (c.576T>A, p.Tyr1928) and three new variants of unknown significance (VUSs) in IL17RD (c.960G>A, p.Met320Ile), FGF17 (c.208G>A, p.Gly70Arg), and DUSP6 (c.434T>G, p.Leu145Arg). All were present in the heterozygous state. Previously reported heterozygous variants were also found in the PROK2 (c.163del, p.Ile55*), CHD7 (c.c.2750C>T, p.Thr917Met and c.7891C>T, p.Arg2631*), FLRT3 (c.1106C>T, p.Ala369Val), and CCDC103 (c.461A>C, p.His154Pro) genes. Molecular modeling, molecular dynamics, and conservation analyses were performed on three out of the nine variants identified in our patients, namely, FGF17 (p.Gly70Arg), DUSP6 (p.Leu145Arg), and CHD7 p.(Thr917Met). Except for DUSP6, where the L145R variant was shown to disrupt the interaction between ß6 and ß3, needed for extracellular signal-regulated kinase 2 (ERK2) binding and recognition, no significant changes were identified between the wild-types and mutants of the other proteins. We found a new pathogenic variant of the CHD7 gene. The molecular modeling results suggest that the VUS of the DUSP6 (c.434T>G, p.Leu145Arg) gene may play a role in the pathogenesis of cHH. However, our analysis indicates that it is unlikely that the VUSs for the IL17RD (c.960G>A, p.Met320Ile) and FGF17 (c.208G>A, p.Gly70Arg) genes are involved in the pathogenesis of cHH. Functional studies are needed to confirm this hypothesis.

Towards a Long-Read Sequencing Approach for the Molecular Diagnosis of RPGRORF15 Genetic Variants.

Sequencing of the low-complexity ORF15 exon of RPGR, a gene correlated with retinitis pigmentosa and cone dystrophy, is difficult to achieve with NGS and Sanger sequencing. False results could lead to the inaccurate annotation of genetic variants in dbSNP and ClinVar databases, tools on which HGMD and Ensembl rely, finally resulting in incorrect genetic variants interpretation. This paper aims to propose PacBio sequencing as a feasible method to correctly detect genetic variants in low-complexity regions, such as the ORF15 exon of RPGR, and interpret their pathogenicity by structural studies. Biological samples from 75 patients affected by retinitis pigmentosa or cone dystrophy were analyzed with NGS and repeated with PacBio. The results showed that NGS has a low coverage of the ORF15 region, while PacBio was able to sequence the region of interest and detect eight genetic variants, of which four are likely pathogenic. Furthermore, molecular modeling and dynamics of the RPGR Glu-Gly repeats binding to TTLL5 allowed for the structural evaluation of the variants, providing a way to predict their pathogenicity. Therefore, we propose PacBio sequencing as a standard procedure in diagnostic research for sequencing low-complexity regions such as RPGRORF15, aiding in the correct annotation of genetic variants in online databases.

A novel complex genomic rearrangement affecting the KCNJ2 regulatory region causes a variant of Cooks syndrome.

Cooks syndrome (CS) is an ultrarare limb malformation due to in tandem microduplications involving KCNJ2 and extending to the 5' regulatory element of SOX9. To date, six CS families were resolved at the molecular level. Subsequent studies explored the evolutionary and pathological complexities of the SOX9-KCNJ2/Sox9-Kcnj2 locus, and suggested a key role for the formation of novel topologically associating domain (TAD) by inter-TAD duplications in causing CS. Here, we report a unique case of CS associated with a de novo 1;17 translocation affecting the KCNJ2 locus. On chromosome 17, the breakpoint mapped between KCNJ16 and KCNJ2, and combined with a ~ 5 kb deletion in the 5' of KCNJ2. Based on available capture Hi-C data, the breakpoint on chromosome 17 separated KCNJ2 from a putative enhancer. Gene expression analysis demonstrated downregulation of KCNJ2 in both patient's blood cells and cultured skin fibroblasts. Our findings suggest that a complex rearrangement falling in the 5' of KCNJ2 may mimic the developmental consequences of in tandem duplications affecting the SOX9-KCNJ2/Sox9-Kcnj2 locus. This finding adds weight to the notion of an intricate role of gene regulatory regions and, presumably, the related three-dimensional chromatin structure in normal and abnormal human morphology.

An improved NMR approach for metabolomics of intact serum samples.

NMR metabolomics has inherent capabilities for studying biofluids, such as reproducibility, minimal sample preparation, non-destructiveness, and molecular structure elucidation; however, reliable quantitation of metabolites is still a challenge because of the complex matrix of the samples. The serum is one of the most common samples in clinical studies but possibly the most difficult for NMR analysis because of the high content of proteins, which hampers the detection and quantification of metabolites. Different processes for protein removal, such as ultrafiltration and precipitation, have been proposed, but require sample manipulation, increase time and cost, and possibly lead to loss of information in the metabolic profile. Alternative methods that rely on filtering protein signals by NMR pulse sequencing are commonly used, but standardisation of acquisition parameters and spectra calibration is far from being reached. The present technical note is a critical assessment of the sparsely suggested calibrants, pulse sequences and acquisition parameters toward an optimised combination of the three for accurate and reproducible quantification of metabolites in intact serum.

The transcriptome profile of human trisomy 21 blood cells.

BACKGROUND: Trisomy 21 (T21) is a genetic alteration characterised by the presence of an extra full or partial human chromosome 21 (Hsa21) leading to Down syndrome (DS), the most common form of intellectual disability (ID). It is broadly agreed that the presence of extra genetic material in T21 gives origin to an altered expression of genes located on Hsa21 leading to DS phenotype. The aim of this study was to analyse T21 and normal control blood cell gene expression profiles obtained by total RNA sequencing (RNA-Seq). RESULTS: The results were elaborated by the TRAM (Transcriptome Mapper) software which generated a differential transcriptome map between human T21 and normal control blood cells providing the gene expression ratios for 17,867 loci. The obtained gene expression profiles were validated through real-time reverse transcription polymerase chain reaction (RT-PCR) assay and compared with previously published data. A post-analysis through transcriptome mapping allowed the identification of the segmental (regional) variation of the expression level across the whole genome (segment-based analysis of expression). Interestingly, the most over-expressed genes encode for interferon-induced proteins, two of them (MX1 and MX2 genes) mapping on Hsa21 (21q22.3). The altered expression of genes involved in mitochondrial translation and energy production also emerged, followed by the altered expression of genes encoding for the folate cycle enzyme, GART, and the folate transporter, SLC19A1. CONCLUSIONS: The alteration of these pathways might be linked and involved in the manifestation of ID in DS.

Spectral-Domain Optical Coherence Tomography Analysis in Syndromic and Nonsyndromic Forms of Retinitis Pigmentosa due to USH2A Genetic Variants.

INTRODUCTION: This study aimed to analyze macular structure by using spectral-domain optical coherence tomography (SD-OCT) in a cohort of patients affected by autosomal recessive retinitis pigmentosa and Usher syndrome, due to genetic variants in USH2A gene, and to correlate optical coherence tomography (OCT) parameters with functional and genetic data. METHODS: The subjects of this study were 92 patients, 46 syndromic (Usher syndrome type IIa [Ush2]) and 46 nonsyndromic (autosomal recessive RP [arRP]), with clinical and genetic diagnosis of USH2A-related retinal dystrophy, who underwent a complete ophthalmic examination and spectral-domain OCT analysis. The study focused on evaluating the differences between the 2 groups in the following parameters: best-corrected visual acuity (BCVA), ellipsoid zone (EZ) width, presence of epiretinal membrane (ERM), and cystic macular lesions (CMLs). Variants in USH2A gene were divided into 3 categories, according to the expected impact (low/high) at protein level of the different variants on each allele. RESULTS: BCVA and EZ width were significantly lower in Ush2 than in arRP patients (p < 0.0001 and p = 0.001). ERM was detected in 34.8% (16/46) of arRP patients and in 65.2% (30/46) of Ush2 patients (p = 0.003). CML was detected in 17.4% (8/46) of arRP patients and 30.4% (14/46) of Ush2 patients (p = 0.14). The allelic distribution was statistically different (p = 0.0003) by dividing the 2 diseases: for Ush2 patients it was 45.7% (high/high), 39.1% (low/high) and 15.2% (low/low); for arRP patients it was 8.7% (high/high), 56.5% (low/high), and 34.8% (low/low). The severity class of the variants significantly affected visual acuity and EZ width parameters (p = 0.004 and p = 0.002, respectively). CONCLUSION: Retinal disease, as evaluated by means of SD-OCT, shows more advanced degeneration signs in the syndromic than the nonsyndromic form of retinal dystrophy related to USH2A gene. Variant types and allelic profiles are determining factors for the onset of syndromic features. However, since the 3 allelic profiles can be found in both Usher and RP patients, other factors must necessarily play a determining role.

Low Efficacy of Genetic Tests for the Diagnosis of Primary Lymphedema Prompts Novel Insights into the Underlying Molecular Pathways.

Lymphedema is a chronic inflammatory disorder caused by ineffective fluid uptake by the lymphatic system, with effects mainly on the lower limbs. Lymphedema is either primary, when caused by genetic mutations, or secondary, when it follows injury, infection, or surgery. In this study, we aim to assess to what extent the current genetic tests detect genetic variants of lymphedema, and to identify the major molecular pathways that underlie this rather unknown disease. We recruited 147 individuals with a clinical diagnosis of primary lymphedema and used established genetic tests on their blood or saliva specimens. Only 11 of these were positive, while other probands were either negative (63) or inconclusive (73). The low efficacy of such tests calls for greater insight into the underlying mechanisms to increase accuracy. For this purpose, we built a molecular pathways diagram based on a literature analysis (OMIM, Kegg, PubMed, Scopus) of candidate and diagnostic genes. The PI3K/AKT and the RAS/MAPK pathways emerged as primary candidates responsible for lymphedema diagnosis, while the Rho/ROCK pathway appeared less critical. The results of this study suggest the most important pathways involved in the pathogenesis of lymphedema, and outline the most promising diagnostic and candidate genes to diagnose this disease.

A next generation sequencing gene panel for use in the diagnosis of anorexia nervosa.

PURPOSE: The aim of this study was to increase knowledge of genes associated with anorexia nervosa (AN) and their diagnostic offer, using a next generation sequencing (NGS) panel for the identification of genetic variants. The rationale underlying this test is that we first analyze the genes associated with syndromic forms of AN, then genes that were found to carry rare variants in AN patients who had undergone segregation analysis, and finally candidate genes intervening in the same molecular pathways or identified by GWAS or in mouse models. METHODS: We developed an NGS gene panel and used it to screen 68 Italian AN patients (63 females, 5 males). The panel included 162 genes. Family segregation study was conducted on available relatives of probands who reported significant genetic variants. RESULTS: In our analysis, we found potentially deleterious variants in 2 genes (PDE11A and SLC25A13) associated with syndromic forms of anorexia and predicted deleterious variants in the following 12 genes: CD36, CACNA1C, DRD4, EPHX2, ESR1, GRIN2A, GRIN3B, LRP2, NPY4R, PTGS2, PTPN22 and SGPP2. Furthermore, by Sanger sequencing of the promoter region of NNAT, we confirmed the involvement of this gene in the pathogenesis of AN. Family segregation studies further strengthened the possible causative role of CACNA1C, DRD4, GRIN2A, PTGS2, SGPP2, SLC25A13 and NNAT genes in AN etiology. CONCLUSION: The major finding of our study is the confirmation of the involvement of the NNAT gene in the pathogenesis of AN; furthermore, this study suggests that NGS-based testing can play an important role in the diagnostic evaluation of AN, excluding syndromic forms and increasing knowledge of the genetic etiology of AN. LEVEL OF EVIDENCE: Level I, experimental study.

A Novel GUCA1A Variant Associated with Cone Dystrophy Alters cGMP Signaling in Photoreceptors by Strongly Interacting with and Hyperactivating Retinal Guanylate Cyclase.

Guanylate cyclase-activating protein 1 (GCAP1), encoded by the GUCA1A gene, is a neuronal calcium sensor protein involved in shaping the photoresponse kinetics in cones and rods. GCAP1 accelerates or slows the cGMP synthesis operated by retinal guanylate cyclase (GC) based on the light-dependent levels of intracellular Ca2+, thereby ensuring a timely regulation of the phototransduction cascade. We found a novel variant of GUCA1A in a patient affected by autosomal dominant cone dystrophy (adCOD), leading to the Asn104His (N104H) amino acid substitution at the protein level. While biochemical analysis of the recombinant protein showed impaired Ca2+ sensitivity of the variant, structural properties investigated by circular dichroism and limited proteolysis excluded major structural rearrangements induced by the mutation. Analytical gel filtration profiles and dynamic light scattering were compatible with a dimeric protein both in the presence of Mg2+ alone and Mg2+ and Ca2+. Enzymatic assays showed that N104H-GCAP1 strongly interacts with the GC, with an affinity that doubles that of the WT. The doubled IC50 value of the novel variant (520 nM for N104H vs. 260 nM for the WT) is compatible with a constitutive activity of GC at physiological levels of Ca2+. The structural region at the interface with the GC may acquire enhanced flexibility under high Ca2+ conditions, as suggested by 2 µs molecular dynamics simulations. The altered interaction with GC would cause hyper-activity of the enzyme at both low and high Ca2+ levels, which would ultimately lead to toxic accumulation of cGMP and Ca2+ in the photoreceptor outer segment, thus triggering cell death.

Impaired Ca2+ Sensitivity of a Novel GCAP1 Variant Causes Cone Dystrophy and Leads to Abnormal Synaptic Transmission Between Photoreceptors and Bipolar Cells.

Guanylate cyclase-activating protein 1 (GCAP1) is involved in the shutdown of the phototransduction cascade by regulating the enzymatic activity of retinal guanylate cyclase via a Ca2+/cGMP negative feedback. While the phototransduction-associated role of GCAP1 in the photoreceptor outer segment is widely established, its implication in synaptic transmission to downstream neurons remains to be clarified. Here, we present clinical and biochemical data on a novel isolate GCAP1 variant leading to a double amino acid substitution (p.N104K and p.G105R) and associated with cone dystrophy (COD) with an unusual phenotype. Severe alterations of the electroretinogram were observed under both scotopic and photopic conditions, with a negative pattern and abnormally attenuated b-wave component. The biochemical and biophysical analysis of the heterologously expressed N104K-G105R variant corroborated by molecular dynamics simulations highlighted a severely compromised Ca2+-sensitivity, accompanied by minor structural and stability alterations. Such differences reflected on the dysregulation of both guanylate cyclase isoforms (RetGC1 and RetGC2), resulting in the constitutive activation of both enzymes at physiological levels of Ca2+. As observed with other GCAP1-associated COD, perturbation of the homeostasis of Ca2+ and cGMP may lead to the toxic accumulation of second messengers, ultimately triggering cell death. However, the abnormal electroretinogram recorded in this patient also suggested that the dysregulation of the GCAP1-cyclase complex further propagates to the synaptic terminal, thereby altering the ON-pathway related to the b-wave generation. In conclusion, the pathological phenotype may rise from a combination of second messengers' accumulation and dysfunctional synaptic communication with bipolar cells, whose molecular mechanisms remain to be clarified.

Complete Androgen Insensitivity Syndrome: From the Relevance of an Accurate Genetic Diagnosis to the Challenge of Clinical Management. A Case Report.

Introduction: Androgen insensitivity syndrome (AIS), an X-linked recessive disorder of sex development (DSD), is caused by variants of the androgen receptor (AR) gene, mapping in the long arm of the X chromosome, which cause a complete loss of function of the receptor. Case presentation: We report a patient diagnosed with complete AIS (CAIS) at birth due to swelling in the bilateral inguinal region. Transabdominal ultrasound revealed the absence of the uterus and ovaries and the presence of bilateral testes in the inguinal region. The karyotype was 46,XY. She underwent bilateral orchiectomy at 9 months and was given estrogen substitutive therapy at the age of 11 years. Genetic analysis of the AR gene variants was requested when, at the age of 20, the patient came to our observation. Methods: The genetic testing was performed by next-generation sequence (NGS) analysis. Results: The genetic analysis showed the presence of the c.2242T>A, p.(Phe748Ile) variant in the AR gene. To the best of our knowledge, this variant has not been published so far. Furthermore, the patient has a heterozygous c.317A>G, p.(Gln106Arg) variation of the gonadotropin-releasing hormone receptor (GNRHR) gene, a heterozygous c.2273G>A, p.Arg758His variation of the chromodomain helicase DNA binding protein 7 (CHD7) gene, and compound heterozygous c.875A>G, p.Tyr292Cys, and c.8023A>G, p.Ile2675Val variations of the Dynein Axonemal Heavy Chain 11 (DNAH11) gene. Conclusions: The case herein reported underlines the importance of an accurate genetic analysis that has to include karyotype and AR gene variant analysis. This is useful to confirm a clinical diagnosis and establish the proper management of patients with CAIS. Numerous variants of the AR gene have not yet been identified. Moreover, several pitfalls are still present in the management of these patients. More studies are needed to answer unresolved questions, and common protocols are required for the clinical follow-up of patients with CAIS.

Adult-onset glutaric aciduria type I: rare presentation of a treatable disorder.

Glutaric aciduria type I (GA1; OMIM #231670) is an autosomal recessively inherited and treatable disorder characterized by the accumulation and irregular excretion of glutaric acid due to a defect in the glutaryl-CoA dehydrogenase enzyme involved in the catabolic pathways of L-lysine, L-hydroxylysine, and L-tryptophan. Glutaryl-CoA dehydrogenase is encoded by the GCDH gene (OMIM #608801), and several mutations in this gene are known to result in GA1. GA1 usually presents in the first 18-36 months of life with mild or severe acute encephalopathy, movement disorders, and striatal degeneration. Few cases of adult-onset GA1 have been described so far in the literature, often with non-specific and sometimes longstanding neurological symptoms. Since a preventive metabolic treatment is available, neurologists must be aware of this rare but likely underdiagnosed presentation, especially when typical neuroimaging features are identified. Here, we describe 35-year-old presenting with headache and subjective memory problems. There was no history of dystonic movement disorders. Neurological examination and neurocognitive tests were normal. Brain MRI scan revealed white matter abnormalities associated with subependymal nodules and mild frontotemporal hypoplasia suggestive of glutaric aciduria type 1 (GA1). Genetic testing confirmed the presence of homozygous c.1204C > T (p.R402W) variant in the GCDH gene, inherited from heterozygous parents.

A novel p.(Glu111Val) missense mutation in GUCA1A associated with cone-rod dystrophy leads to impaired calcium sensing and perturbed second messenger homeostasis in photoreceptors.

Guanylate Cyclase-Activating Protein 1 (GCAP1) regulates the enzymatic activity of the photoreceptor guanylate cyclases (GC), leading to inhibition or activation of the cyclic guanosine monophosphate (cGMP) synthesis depending on its Ca2+- or Mg2+-loaded state. By genetically screening a family of patients diagnosed with cone-rod dystrophy, we identified a novel missense mutation with autosomal dominant inheritance pattern (c.332A>T; p.(Glu111Val); E111V from now on) in the GUCA1A gene coding for GCAP1. We performed a thorough biochemical and biophysical investigation of wild type (WT) and E111V human GCAP1 by heterologous expression and purification of the recombinant proteins. The E111V substitution disrupts the coordination of the Ca2+ ion in the high-affinity site (EF-hand 3, EF3), thus significantly decreasing the ability of GCAP1 to sense Ca2+ (∼80-fold higher Kdapp compared to WT). Both WT and E111V GCAP1 form dimers independently on the presence of cations, but the E111V Mg2+-bound form is prone to severe aggregation over time. Molecular dynamics simulations suggest a significantly increased flexibility of both the EF3 and EF4 cation binding loops for the Ca2+-bound form of E111V GCAP1, in line with the decreased affinity for Ca2+. In contrast, a more rigid backbone conformation is observed in the Mg2+-bound state compared to the WT, which results in higher thermal stability. Functional assays confirm that E111V GCAP1 interacts with the target GC with a similar apparent affinity (EC50); however, the mutant shifts the GC inhibition out of the physiological [Ca2+] (IC50E111V ∼10 µM), thereby leading to the aberrant constitutive synthesis of cGMP under conditions of dark-adapted photoreceptors.

A very early diagnosis of AlstrÓ§m syndrome by next generation sequencing.

BACKGROUND: Alström syndrome is a rare recessively inherited disorder caused by variants in the ALMS1 gene. It is characterized by multiple organ dysfunction, including cone-rod retinal dystrophy, dilated cardiomyopathy, hearing loss, obesity, insulin resistance, hyperinsulinemia, type 2 diabetes mellitus and systemic fibrosis. Heterogeneity and age-dependent development of clinical manifestations make it difficult to obtain a clear diagnosis, especially in pediatric patients. CASE PRESENTATION: Here we report the case of a girl with Alström syndrome. Genetic examination was proposed at age 22 months when suspected macular degeneration was the only major finding. Next generation sequencing of a panel of genes linked to eye-related pathologies revealed two compound heterozygous variants in the ALMS1 gene. Frameshift variants c.1196_1202del, p.(Thr399Lysfs*11), rs761292021 and c.11310_11313del, (p.Glu3771Trpfs*18), rs747272625 were detected in exons 5 and 16, respectively. Both variants cause frameshifts and generation of a premature stop-codon that probably leads to mRNA nonsense-mediated decay. Validation and segregation of ALMS1 variants were confirmed by Sanger sequencing. CONCLUSIONS: Genetic testing makes it possible, even in childhood, to increase the number of correct diagnoses of patients who have ambiguous phenotypes caused by rare genetic variants. The development of high-throughput sequencing technologies offers an exceptionally valuable screening tool for clear genetic diagnoses and ensures early multidisciplinary management and treatment of the emerging symptoms.

FOXC2 Disease Mutations Identified in Lymphedema Distichiasis Patients Impair Transcriptional Activity and Cell Proliferation.

FOXC2 is a member of the human forkhead-box gene family and encodes a regulatory transcription factor. Mutations in FOXC2 have been associated with lymphedema distichiasis (LD), an autosomal dominant disorder that primarily affects the limbs. Most patients also show extra eyelashes, a condition known as distichiasis. We previously reported genetic and clinical findings in six unrelated families with LD. Half the patients showed missense mutations, two carried frameshift mutations and a stop mutation was identified in a last patient. Here we analyzed the subcellular localization and transactivation activity of the mutant proteins, showing that all but one (p.Y109*) localized to the nucleus. A significant reduction of transactivation activity was observed in four mutants (p.L80F, p.H199Pfs*264, p.I213Tfs*18, p.Y109*) compared with wild type FOXC2 protein, while only a partial loss of function was associated with p.V228M. The mutant p.I213V showed a very slight increase of transactivation activity. Finally, immunofluorescence analysis revealed that some mutants were sequestered into nuclear aggregates and caused a reduction of cell viability. This study offers new insights into the effect of FOXC2 mutations on protein function and shows the involvement of aberrant aggregation of FOXC2 proteins in cell death.

Aldo-Keto Reductase 1C1 (AKR1C1) as the First Mutated Gene in a Family with Nonsyndromic Primary Lipedema.

Lipedema is an often underdiagnosed chronic disorder that affects subcutaneous adipose tissue almost exclusively in women, which leads to disproportionate fat accumulation in the lower and upper body extremities. Common comorbidities include anxiety, depression, and pain. The correlation between mood disorder and subcutaneous fat deposition suggests the involvement of steroids metabolism and neurohormones signaling, however no clear association has been established so far. In this study, we report on a family with three patients affected by sex-limited autosomal dominant nonsyndromic lipedema. They had been screened by whole exome sequencing (WES) which led to the discovery of a missense variant p.(Leu213Gln) in AKR1C1, the gene encoding for an aldo-keto reductase catalyzing the reduction of progesterone to its inactive form, 20-α-hydroxyprogesterone. Comparative molecular dynamics simulations of the wild-type vs. variant enzyme, corroborated by a thorough structural and functional bioinformatic analysis, suggest a partial loss-of-function of the variant. This would result in a slower and less efficient reduction of progesterone to hydroxyprogesterone and an increased subcutaneous fat deposition in variant carriers. Overall, our results suggest that AKR1C1 is the first candidate gene associated with nonsyndromic lipedema.