Characterization of AR-CGD female patient with a novel homozygous deletion in CYBC1 gene presenting with unusual clinical phenotype.

Chronic granulomatous disease (CGD) is a human IEI caused by mutations in genes encoding the NADPH oxidase subunits, the enzyme responsible for the respiratory burst. CGD patients have severe life-threatening infections, hyperinflammation and immune dysregulation. Recently, an additional autosomal recessive AR-CGD (type 5) caused by mutations in CYBC1/EROS gene was identified. We report a AR-CGD5 patient with a novel loss of function (LOF) homozygous deletion c.8_7del in the CYBC1 gene including the initiation ATG codon that leads to failure of CYBC1/EROS protein expression and presenting with an unusual clinical manifestation of childhood-onset sarcoidosis-like disease requiring multiple immunosuppressive therapies. We described an abnormal gp91phox protein expression/function in the patient's neutrophils and monocytes (about 50%) and a severely compromised B cell subset (gp91phox < 15%; DHR+ < 4%). Our case-report emphasized the importance of considering a diagnosis of AR-CGD5 deficiency even in absence of typical clinical and laboratory findings.

Coexistence of Genetic Diseases Is a New Clinical Challenge: Three Unrelated Cases of Dual Diagnosis.

Technological advancements in molecular genetics and cytogenetics have led to the diagnostic definition of complex or atypical clinical pictures. In this paper, a genetic analysis identifies multimorbidities, one due to either a copy number variant or a chromosome aneuploidy, and a second due to biallelic sequence variants in a gene associated with an autosomal recessive disorder. We diagnosed the simultaneous presence of these conditions, which co-occurred by chance, in three unrelated patients: a 10q11.22q11.23 microduplication and a homozygous variant, c.3470A>G (p.Tyr1157Cys), in the WDR19 gene associated with autosomal recessive ciliopathy; down syndrome and two variants, c.850G>A; p.(Gly284Arg) and c.5374G>T; p.(Glu1792*), in the LAMA2 gene associated with merosin-deficient congenital muscular dystrophy type 1A (MDC1A); and a de novo 16p11.2 microdeletion syndrome and homozygous variant, c.2828G>A (p.Arg943Gln), in the ABCA4 gene associated with Stargardt disease 1 (STGD1). The possibility of being affected by two relatively common or rare inherited genetic conditions would be suspected when signs and symptoms are incoherent with the primary diagnosis. All this could have important implications for improving genetic counseling, determining the correct prognosis, and, consequently, organizing the best long-term follow-up.

A Novel Autosomal Recessive Variant of the NRL Gene Causing Enhanced S-Cone Syndrome: A Morpho-Functional Analysis of Two Unrelated Pediatric Patients.

Enhanced S-cone syndrome (ESCS) is a rare autosomal recessive retinal degeneration mainly associated with pathogenic variations in the NR2E3 gene. Only a few pathogenic variations in the NRL gene associated with ESCS have been reported to date. Here, we describe the clinical and genetic findings of two unrelated pediatric patients with a novel frameshift homozygous variant in the NRL gene. Fundus examinations showed signs of peripheral degeneration in both patients, more severe in Proband 2, with relative sparing of the macular area. Spectral domain optical coherence tomography (SD-OCT) revealed a significant macular involvement with cysts in Proband 1, and minimal foveal alteration with peripheral retina involvement in Proband 2. Visual acuity was abnormal in both patients, but more severely affected in Proband 1 than Proband 2. The electroretinogram recordings showed reduced scotopic, mixed and single flash cone responses, with a typical supernormal S-cone response, meeting the criteria for a clinical diagnosis of ESCS in both patients. The present report expands the clinical and genetic spectrum of NRL-associated ESCS, and confirms the age-independent variability of phenotypic presentation already described in the NR2E3-associated ESCS.

Genetics of Inherited Retinal Diseases in Understudied Ethnic Groups in Italian Hospitals.

Purpose: Describing the clinical and genetic features of an ethnically heterogeneous group of (inherited retinal diseases) IRD patients from different underrepresented countries, referring to specialized Italian Hospitals, and expanding the epidemiological spectrum of the IRD in understudied populations. Methods: The patients' phenotypes underwent were characterized by exhaustive ophthalmological examinations, including morpho-functional testing. Genetic testing was performed using next-generation sequencing (NGS) and gene sequencing panels targeting a specific set of genes, Sanger sequencing and-when necessary-multiplex ligation-dependent probe amplification (MLPA) to better identify the genotype. When possible, segregation analysis was performed in order to confirm unsolved cases. Results: The article reports the results of the phenotypes and genotypes of 123 IRD probands, 69 males and 54 females, mean age 41 (IQR, 54-30) years, disease onset at 13 (IQR, 27.25-5) years. Thirty-three patients out of 123 (26.8%) were Africans (North/Northwest Africa), 21 (17.1%) Asians, 19 (15.4%) Americans (South/Central America) and 50 (40.7%) Europeans (Eastern Europe). Retinitis pigmentosa was the most represented phenotype (56%), followed by cone dystrophy (11%) and Leber congenital amaurosis (7%), while ABCA4 was the most frequently mutated gene (18%), followed by USH2A (9%) and RPGR (5%). About ABCA4 variants found in Stargardt disease, macular and cone dystrophies were predominant in Asian (42%) and European (21%) patients. The most represented inheritance pattern was autosomal recessive, while a higher frequency of homozygous patients versus compound heterozygotes as compared to previous studies on Italian IRD patients was evidenced, reflecting a possible higher frequency of inbreeding marriages. Conclusion: Though limited by the relatively low number of patients, the present paper paints a picture of the clinical and genetic features of IRD patients from understudied ethnic groups referred to Italian specialized hospitals and extended the epidemiological studies on underrepresented world regional areas.

Identification of a Novel Mutation in TNFAIP3 in a Family With Poly-Autoimmunity.

Haploinsufficiency of A20 (HA20) is an inflammatory disease caused by mutations in the TNFAIP3 gene classically presenting with Behcet's-like disease. A20 acts as an inhibitor of inflammation through its effect on NF-kB pathway. Here we describe four consanguineous patients (three sisters and their mother) with a predominantly autoimmune phenotype, including thyroiditis, type I diabetes, hemolytic anemia and chronic polyarthritis. All patients had recurrent oral ulcers, with only 1 patient presenting also recurrent fever episodes, as a classical autoinflammatory feature. Next generation sequencing identified a novel heterozygous frameshift mutation (p.His577Alafs*95) that causes a premature stop codon in the zinc finger domain of A20, leading to a putative haploinsufficiency of the protein. Functional analyses confirmed the pathogenicity of the mutation. The variant was associated with decreased levels of A20 in blood cells. Accordingly, ex-vivo lipopolysaccharide (LPS)-stimulated patients' peripheral blood mononuclear cells (PBMCs) showed higher levels of p65 NF-kB phosphorylation, as well as increased production of the proinflammatory cytokines IL-1ß, IL-6 and TNF-α. Moreover, in agreement with recent observations, demonstrating a role for A20 in inhibiting STAT1 and IFNγ pathways, markedly higher circulating levels of the two IFNγ-inducible chemokines CXCL9 and CXCL10 were detected in all patients. Supporting the findings of a hyperactivation of IFNγ signaling pathway in HA20 patients, patients' monocytes showed higher levels of STAT1 without stimulation, as well as higher phosphorylated (active) STAT1 levels following IFNγ stimulation. In conclusion, our study show that in the clinical spectrum of HA20 autoimmune features may predominate over autoinflammatory features and demonstrate, from a molecular point of view, the involvement of A20 in modulating not only the NF-kB, but also the IFNγ pathway.

Blue Cone Monochromatism with Foveal Hypoplasia Caused by the Concomitant Effect of Variants in OPN1LW/OPN1MW and GPR143 Genes.

Blue cone monochromatism (BCM) is an X-linked recessive cone dysfunction disorder caused by mutations in the OPN1LW/OPN1MW gene cluster, encoding long (L)- and middle (M)-wavelength-sensitive cone opsins. Here, we report on the unusual clinical presentation of BCM caused by a novel mutation in the OPN1LW gene in a young man. We describe in detail the phenotype of the proband, and the subclinical morpho-functional anomalies shown by his carrier mother. At a clinical level, the extensive functional evaluation demonstrated in the proband the M/L cone affection and the sparing of S-cone function, distinctive findings of BCM. Interestingly, spectral-domain optical coherence tomography showed the presence of foveal hypoplasia with focal irregularities of the ellipsoid layer in the foveal area, reported to be associated with some cases of cone-rod dystrophy and achromatopsia. At a molecular level, we identified the novel mutation c.427T > C p.(Ser143Pro) in the OPN1LW gene and the common missense mutation c.607T > C (p.Cys203Arg) in the OPN1MW gene. In addition, we discovered the c.768-2_769delAGTT splicing variant in the GPR143 gene. To our knowledge, this is the first case of foveal hypoplasia in a BCM patient and of mild clinical affection in a female carrier caused by the concomitant effect of variants in OPN1LW/OPN1MW and GPR143 genes, thus as the result of the simultaneous action of two independent genetic defects.

Clinical and Molecular Aspects of the Neurodevelopmental Disorder Associated with PAK3 Perturbation.

X-linked intellectual disability can be diagnosed in about 10-12% of intellectually disabled males. In the past, mutations affecting the PAK3 gene (p21 protein-activated kinase 3, MIM#300142) have been associated with a non-syndromic form of X-linked intellectual disability, which has to date been identified in a limited number of families.Since this neurodevelopmental disorder mostly afflicts males, descriptions of symptomatic female carriers are quite rare.We describe a female patient with neurodevelopmental delay and a novel PAK3 variant. Interestingly, she manifests craniofacial anomalies, including microcephaly, representing the second reported microcephalic female but the first for whom a detailed clinical description is available. She also displays other uncommon clinical findings, which we illustrate.Moreover, a comprehensive clinical and molecular review of all to date published patients has been made. This study contributes to further delineate the PAK3-related phenotype, which can be considered a non-syndromic X-linked intellectual disability, with seemingly recurrent craniofacial abnormalities.

Early Treatment and IL1RN Single-Nucleotide Polymorphisms Affect Response to Anakinra in Systemic Juvenile Idiopathic Arthritis.

OBJECTIVE: To evaluate the impact of early treatment and IL1RN genetic variants on the response to anakinra in systemic juvenile idiopathic arthritis (JIA). METHODS: Response to anakinra was defined as achievement of clinically inactive disease (CID) at 6 months without glucocorticoid treatment. Demographic, clinical, and laboratory characteristics of 56 patients were evaluated in univariate and multivariate analyses as predictors of response to treatment. Six single-nucleotide polymorphisms (SNPs) in the IL1RN gene, previously demonstrated to be associated with a poor response to anakinra, were genotyped by quantitative polymerase chain reaction (qPCR) or Sanger sequencing. Haplotype mapping was performed with Haploview software. IL1RN messenger RNA (mRNA) expression in whole blood from patients, prior to anakinra treatment initiation, was assessed by qPCR. RESULTS: After 6 months of anakinra treatment, 73.2% of patients met the criteria for CID without receiving glucocorticoids. In the univariate analysis, the variable most strongly related to the response was disease duration from onset to initiation of anakinra treatment, with an optimal cutoff at 3 months (area under the curve 84.1%). Patients who started anakinra treatment ≥3 months after disease onset had an 8-fold higher risk of nonresponse at 6 months of treatment. We confirmed that the 6 IL1RN SNPs were inherited as a common haplotype. We found that homozygosity for ≥1 high-expression SNP correlated with higher IL1RN mRNA levels and was associated with a 6-fold higher risk of nonresponse, independent of disease duration. CONCLUSION: Our findings on patients with systemic JIA confirm the important role of early interleukin-1 inhibition and suggest that genetic IL1RN variants predict nonresponse to therapy with anakinra.

IFNAR2 Deficiency Causing Dysregulation of NK Cell Functions and Presenting With Hemophagocytic Lymphohistiocytosis.

We describe a 2 year old boy with two previously undescribed frameshift mutations in the interferon (IFN)α/ß receptor 2 (IFNAR2) gene presenting with hemophagocytic lymphohistiocytosis (HLH) following measles-mumps-rubella vaccination. Functional analyses show the absence of response to type I IFN in the patient's cells, as revealed by the lack of phosphorylation of STAT1 and the lack of induction of interferon-stimulated genes upon ex vivo stimulation with IFNα. HLH has been reported in patients with inborn errors of type I IFN-mediated immune responses following vaccination with live-attenuated viruses. The relation between HLH and defective type I IFN-mediated responses is unclear. We show that in patient's natural killer (NK) cells stimulated with IFNα the expected increase in degranulation and inhibition of IFNγ production were affected. These data support a role for NK cell function dysregulation and lack of inhibition of IFNγ production as contributors to the development of HLH in patients with impaired type I IFN signaling.

Expression profiles of the SARS-CoV-2 host invasion genes in nasopharyngeal and oropharyngeal swabs of COVID-19 patients.

We collect the nasopharyngeal and oropharyngeal swabs of 63 subjects with severe symptoms or contacts with COVID-19 confirmed cases to perform a pilot-study aimed to verify the "in situ" expression of SARS-CoV-2 host invasion genes (ACE2, TMPRSS2, PCSK3, EMILIN1, EMILIN2, MMRN1, MMRN2, DPP4). ACE2 (FC = +1.88, p ≤ 0.05) and DPP4 (FC = +3, p < 0.01) genes showed a significant overexpression in COVID-19 patients. ACE2 and DPP4 expression levels had a good performance (AUC = 0.75; p < 0.001) in distinguishing COVID-19 patients from negative subjects. Interestingly, we found a significant positive association of ACE2 mRNA and PCSK3, EMILIN1, MMRN1 and MMRN2 expression and of DPP4 mRNA and EMILIN2 expression only in COVID-19 patients. Noteworthy, a subgroup of severe COVID-19 (n = 7) patients, showed significant high level of ACE2 mRNA and another subgroup of less severe COVID-19 patients (n = 6) significant raised DPP4 levels. These results indicate that a group of SARS-CoV-2 host invasion genes are functionally related in COVID-19 patients and suggests that ACE2 and DPP4 expression level could act as genomic biomarkers. Moreover, at the best of our knowledge, this is the first study that shows an elevated DPP4 expression in naso- and oropharyngeal swabs of COVID-19 patient thus suggesting a functional role of DPP4 in SARS-CoV-2 infections.

HLA allele frequencies and susceptibility to COVID-19 in a group of 99 Italian patients.

With the aim to individuate alleles that may reflect a higher susceptibility to the disease, in the present study we analyzed the HLA allele frequency distribution in a group of 99 Italian patients affected by a severe or extremely severe form of COVID-19. After the application of Bonferroni's correction for multiple tests, a significant association was found for HLA-DRB1*15:01, -DQB1*06:02 and -B*27:07, after comparing the results to a reference group of 1017 Italian individuals, previously typed in our laboratory. The increased frequencies observed may contribute to identify potential markers of susceptibility to the disease, although controversial results on the role of single HLA alleles in COVID-19 patients have been recently reported.

Tumor Necrosis Factor Receptor SF10A (TNFRSF10A) SNPs Correlate With Corticosteroid Response in Duchenne Muscular Dystrophy.

BACKGROUND: Duchenne muscular dystrophy (DMD) is a rare and severe X-linked muscular dystrophy in which the standard of care with variable outcome, also due to different drug response, is chronic off-label treatment with corticosteroids (CS). In order to search for SNP biomarkers for corticosteroid responsiveness, we genotyped variants across 205 DMD-related genes in patients with differential response to steroid treatment. METHODS AND FINDINGS: We enrolled a total of 228 DMD patients with identified dystrophin mutations, 78 of these patients have been under corticosteroid treatment for at least 5 years. DMD patients were defined as high responders (HR) if they had maintained the ability to walk after 15 years of age and low responders (LR) for those who had lost ambulation before the age of 10 despite corticosteroid therapy. Based on interactome mapping, we prioritized 205 genes and sequenced them in 21 DMD patients (discovery cohort or DiC = 21). We identified 43 SNPs that discriminate between HR and LR. Discriminant Analysis of Principal Components (DAPC) prioritized 2 response-associated SNPs in the TNFRSF10A gene. Validation of this genotype was done in two additional larger cohorts composed of 46 DMD patients on corticosteroid therapy (validation cohorts or VaC1), and 150 non ambulant DMD patients and never treated with corticosteroids (VaC2). SNP analysis in all validation cohorts (N = 207) showed that the CT haplotype is significantly associated with HR DMDs confirming the discovery results. CONCLUSION: We have shown that TNFRSF10A CT haplotype correlates with corticosteroid response in DMD patients and propose it as an exploratory CS response biomarker.

Efficacy and Adverse Events During Janus Kinase Inhibitor Treatment of SAVI Syndrome.

OBJECTIVES: Mutations affecting the TMEM173 gene cause STING-associated vasculopathy with onset in infancy (SAVI). No standard immunosuppressive treatment approach is able to control disease progression in patients with SAVI. We studied the efficacy and safety of targeting type I IFN signaling with the Janus kinase inhibitor, ruxolitinib. METHODS: We used DNA sequencing to identify mutations in TMEM173 in patients with peripheral blood type I IFN signature. The JAK1/2 inhibitor ruxolitinib was administered on an off-label basis. RESULTS: We identified three patients with SAVI presenting with skin involvement and progressive severe interstitial lung disease. Indirect echocardiographic signs of pulmonary hypertension were present in one case. Following treatment with ruxolitinib, we observed improvements of respiratory function including increased forced vital capacity in two patients, with discontinuation of oxygen therapy and resolution of echocardiographic abnormalities in one case. Efficacy was persistent in one patient and only transitory in the other two patients. Clinical control of skin complications was obtained, and one patient discontinued steroid treatment. One patient, who presented with kidney involvement, showed resolution of hematuria. One patient experienced increased recurrence of severe viral respiratory infections. Monitoring of peripheral blood type I interferon signature during ruxolitinib treatment did not show a stable decrease. CONCLUSIONS: We conclude that targeting type I IFN receptor signaling may represent a promising therapeutic option for a subset of patients with SAVI syndrome and severe lung involvement. However, the occurrence of viral respiratory infection might represent an important cautionary note for the application of such form of treatment.

Variable Clinical Phenotypes and Relation of Interferon Signature with Disease Activity in ADA2 Deficiency.

OBJECTIVE: An upregulation of type I interferon (IFN) stimulated genes [IFN score (IS)] was described in patients with adenosine deaminase 2 deficiency (DADA2). We describe the clinical course of 5 such patients and the role of IS as a marker of disease activity and severity. METHODS: Expression levels of IS were determined by quantitative real-time PCR. RESULTS: Five white patients were identified as carrying CECR1 mutations. The IS before treatment was elevated in 4 out of 5 patients and decreased after treatment. CONCLUSION: Our data confirm the high variability of DADA2 and suggest type I IS as a biomarker of disease activity.

Transcriptional and epigenetic analyses of the DMD locus reveal novel cis­acting DNA elements that govern muscle dystrophin expression.

The dystrophin gene (DMD) is the largest gene in the human genome, mapping on the Xp21 chromosome locus. It spans 2.2Mb and accounts for approximately 0,1% of the entire human genome. Mutations in this gene cause Duchenne and Becker Muscular Dystrophy, X-linked Dilated Cardiomyopathy, and other milder muscle phenotypes. Beside the remarkable number of reports describing dystrophin gene expression and the pathogenic consequences of the gene mutations in dystrophinopathies, the full scenario of the DMD transcription dynamics remains however, poorly understood. Considering that the full transcription of the DMD gene requires about 16h, we have investigated the activity of RNA Polymerase II along the entire DMD locus within the context of specific chromatin modifications using a variety of chromatin-based techniques. Our results unveil a surprisingly powerful processivity of the RNA polymerase II along the entire 2.2Mb of the DMD locus with just one site of pausing around intron 52. We also discovered epigenetic marks highlighting the existence of four novel cis­DNA elements, two of which, located within intron 34 and exon 45, appear to govern the architecture of the DMD chromatin with implications on the expression levels of the muscle dystrophin mRNA. Overall, our findings provide a global view on how the entire DMD locus is dynamically transcribed by the RNA pol II and shed light on the mechanisms involved in dystrophin gene expression control, which can positively impact on the optimization of the novel ongoing therapeutic strategies for dystrophinopathies.

Congenital heart defects in molecularly proven Kabuki syndrome patients.

The prevalence of congenital heart defects (CHD) in Kabuki syndrome ranges from 28% to 80%. Between January 2012 and December 2015, 28 patients had a molecularly proven diagnosis of Kabuki syndrome. Pathogenic variants in KMT2D (MLL2) were detected in 27 patients, and in KDM6A gene in one. CHD was diagnosed in 19/27 (70%) patients with KMT2D (MLL2) variant, while the single patient with KDM6A change had a normal heart. The anatomic types among patients with CHD included aortic coarctation (4/19 = 21%) alone or associated with an additional CHD, bicuspid aortic valve (4/19 = 21%) alone or associated with an additional CHD, perimembranous subaortic ventricular septal defect (3/19 = 16%), atrial septal defect ostium secundum type (3/19 = 16%), conotruncal heart defects (3/19 = 16%). Additional CHDs diagnosed in single patients included aortic dilatation with mitral anomaly and hypoplastic left heart syndrome. We also reviewed CHDs in patients with a molecular diagnosis of Kabuki syndrome reported in the literature. In conclusion, a CHD is detected in 70% of patients with KMT2D (MLL2) pathogenic variants, most commonly left-sided obstructive lesions, including multiple left-sided obstructions similar to those observed in the spectrum of the Shone complex, and septal defects. Clinical management of Kabuki syndrome should include echocardiogram at the time of diagnosis, with particular attention to left-sided obstructive lesions and mitral anomalies, and annual monitoring for aortic arch dilatation.

Haematological involvement associated with a mild autoinflammatory phenotype, in two patients carrying the E250K mutation of PSTPIP1.

OBJECTIVES: Hyperzincaemia/hypercalprotectinemia (Hz/Hc) syndrome is a recently described condition caused by a specific de novo mutation (E250K) affecting PSTPIP1 gene. It has a phenotype distinct from classical pyogenic arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome that includes severe systemic and cutaneous inflammation, hepatosplenomegaly, arthritis without sequelae, pancytopenia and failure to thrive. METHODS: We describe an 8-year-old boy who presented recurrent right knee swelling mimicking septic arthritis and persistent bone marrow involvement, without cutaneous involvement. RESULTS: Molecular analysis of the PSTPIP1 gene revealed the presence of a heterozygous E250K mutation. No growth failure was detected nor in the patient neither in his mother, carrying the same variant. Blood zinc and calprotectin MRP8/14 concentrations of the patient were found to be markedly increased. Therapy with anakinra was started with rapid disappearance of clinical symptoms and normalization of CRP levels in 24 hours, but persistence of bone marrow involvement. CONCLUSIONS: The patient described has a milder phenotype, with no skin features, minor episodes of arthritis with no sequelae and normal growth. Compared to the patients with de novo mutations described in the literature, familial cases seem to have a milder phenotype. Our case further confirms the lack of efficacy of anakinra on bone marrow involvement.

ADA2 deficiency (DADA2) as an unrecognised cause of early onset polyarteritis nodosa and stroke: a multicentre national study.

OBJECTIVES: To analyse the prevalence of CECR1 mutations in patients diagnosed with early onset livedo reticularis and/or haemorrhagic/ischaemic strokes in the context of inflammation or polyarteritis nodosa (PAN). Forty-eight patients from 43 families were included in the study. METHODS: Direct sequencing of CECR1 was performed by Sanger analysis. Adenosine deaminase 2 (ADA2) enzymatic activity was analysed in monocyte isolated from patients and healthy controls incubated with adenosine and with or without an ADA1 inhibitor. RESULTS: Biallelic homozygous or compound heterozygous CECR1 mutations were detected in 15/48 patients. A heterozygous disease-associated mutation (p.G47V) was observed in two affected brothers. The mean age of onset of the genetically positive patients was 24 months (6 months to 7 years). Ten patients displayed one or more cerebral strokes during their disease course. Low immunoglobulin levels were detected in six patients. Thalidomide and anti-TNF (tumour necrosis factor) blockers were the most effective drugs. Patients without CECR1 mutations had a later age at disease onset, a lower prevalence of neurological and skin manifestations; one of these patients displayed all the clinical features of adenosine deaminase 2deficiency (DADA2) and a defective enzymatic activity suggesting the presence of a missed mutation or a synthesis defect. CONCLUSIONS: DADA2 accounts for paediatric patients diagnosed with PAN-like disease and strokes and might explain an unrecognised condition in patients followed by adult rheumatologist. Timely diagnosis and treatment with anti-TNF agents are crucial for the prevention of severe complications of the disease. Functional assay to measure ADA2 activity should complement genetic testing in patients with non-confirming genotypes.

Deep RNA profiling identified CLOCK and molecular clock genes as pathophysiological signatures in collagen VI myopathy.

Collagen VI myopathies are genetic disorders caused by mutations in collagen 6 A1, A2 and A3 genes, ranging from the severe Ullrich congenital muscular dystrophy to the milder Bethlem myopathy, which is recapitulated by collagen-VI-null (Col6a1(-/-)) mice. Abnormalities in mitochondria and autophagic pathway have been proposed as pathogenic causes of collagen VI myopathies, but the link between collagen VI defects and these metabolic circuits remains unknown. To unravel the expression profiling perturbation in muscles with collagen VI myopathies, we performed a deep RNA profiling in both Col6a1(-/-)mice and patients with collagen VI pathology. The interactome map identified common pathways suggesting a previously undetected connection between circadian genes and collagen VI pathology. Intriguingly, Bmal1(-/-)(also known as Arntl) mice, a well-characterized model displaying arrhythmic circadian rhythms, showed profound deregulation of the collagen VI pathway and of autophagy-related genes. The involvement of circadian rhythms in collagen VI myopathies is new and links autophagy and mitochondrial abnormalities. It also opens new avenues for therapies of hereditary myopathies to modulate the molecular clock or potential gene-environment interactions that might modify muscle damage pathogenesis.