Unveiling the clinical spectrum of relapsing polychondritis: insights into its pathogenesis, novel monogenic causes, and therapeutic strategies.

Relapsing polychondritis is a rare multisystem disease involving cartilaginous and proteoglycan-rich structures. The diagnosis of this disease is mainly suggested by the presence of flares of inflammation of the cartilage, particularly in the ears, nose or respiratory tract, and more rarely, in the presence of other manifestations. The spectrum of clinical presentations may vary from intermittent episodes of painful and often disfiguring auricular and nasal chondritis to an occasional organ or even life-threatening manifestations such as lower airway collapse. There is a lack of awareness about this disease is mainly due to its rarity. In 2020, VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome, a novel autoinflammatory syndrome, was described. VEXAS syndrome is attributed to somatic mutations in methionine-41 of UBA1, the major E1 enzyme that initiates ubiquitylation. This new disease entity connects seemingly unrelated conditions: systemic inflammatory syndromes (relapsing chondritis, Sweet's syndrome, and neutrophilic dermatosis) and hematologic disorders (myelodysplastic syndrome or multiple myeloma). Therefore, this article reviews the current literature on both disease entities.

Description of a novel splice site variant in UBA1 gene causing VEXAS syndrome.

OBJECTIVE: The vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome is a complex immune disorder consequence of somatic UBA1 variants. Most reported pathogenic UBA1 variants are missense or splice site mutations directly impairing the translational start site at p. Met41, with recent studies showing that these variants are frequent causes of recurrent inflammation in older individuals. Here we aimed to characterize a novel UBA1 variant found in two patients clinically presenting with VEXAS syndrome. METHODS: Patients' data were collected from direct assessments and from their medical charts. Genomics analyses were performed by both Sanger and amplicon-based deep sequencing, mRNA studies were performed by both cDNA subcloning and mRNA sequencing. RESULTS: We report a novel, somatic variant in a canonical splice site of the UBA1 gene (c.346-2A>G), which was identified in two unrelated adult male patients with late-onset, unexplained inflammatory manifestations including recurrent fever, Sweet syndrome-like neutrophilic dermatosis, and lung inflammation responsive only to glucocorticoids. RNA analysis from patients' samples demonstrated aberrant mRNA splicing leading to multiple in-frame transcripts, including a transcript retaining the full sequence of intron 4 and a different transcript with the deletion of the first 15 nucleotides of exon 5. CONCLUSION: Here we describe the abnormal UBA1 transcription as a consequence of the novel c.346-2A>G variant identified in two patients with clinical features compatible with VEXAS syndrome. Overall, these results further demonstrate the expanding spectrum of variants in UBA1 leading to pathology and support for a complete gene evaluation in those candidate patients for VEXAS syndrome.

Comparing clinical features between males and females with VEXAS syndrome: data from literature analysis of patient reports.

OBJECTIVES: VEXAS syndrome is an autoinflammatory disease associated with a somatic mutation of the X-linked UBA1 gene in haematopoietic progenitor cells. This disorder was originally described as a disease affecting men, but rare cases of VEXAS syndrome in women have since been reported. The theoretical existence of phenotypic sex differences in this X-linked disease is debated. We compared the features of VEXAS syndrome between males and females to better understand this disorder and to improve its diagnostic accuracy in females. METHODS: From previously published clinical descriptions of VEXAS syndrome, we included studies that described patients with precise, individual VEXAS-related features. We formed a literature-based cohort of patients by collecting their clinical and biological data and compared the characteristics of male and female patients. RESULTS: We gathered 224 patient descriptions from 104 articles: 9 women and 215 men. Among the women, 1 had a constitutional 45, X karyotype and 4 had an acquired X monosomy in the bone marrow karyotype, while the marrow karyotype was not provided for the others. No difference was observed in the clinical or biological features according to sex. We also observed no difference in the type of UBA1 mutation or the association with myelodysplastic syndrome. CONCLUSIONS: Our results supported that UBA1 mutation should be sought under the same conditions in both sexes. As UBA1 is not subject to X-chromosome inactivation, VEXAS syndrome in females requires both UBA1 mutation and X monosomy, thus explaining the similarity between male and female VEXAS-related features and the lower prevalence of VEXAS syndrome in females.

Unveiling the clinical spectrum of relapsing polychondritis: insights into its pathogenesis, novel monogenic causes, and therapeutic strategies

Abstract Relapsing polychondritis is a rare multisystem disease involving cartilaginous and proteoglycan-rich structures. The diagnosis of this disease is mainly suggested by the presence of flares of inflammation of the cartilage, particularly in the ears, nose or respiratory tract, and more rarely, in the presence of other manifestations. The spectrum of clinical presentations may vary from intermittent episodes of painful and often disfiguring auricular and nasal chondritis to an occasional organ or even life-threatening manifestations such as lower airway collapse. There is a lack of awareness about this disease is mainly due to its rarity. In 2020, VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome, a novel autoinflammatory syndrome, was described. VEXAS syndrome is attributed to somatic mutations in methionine-41 of UBA1, the major E1 enzyme that initiates ubiquitylation. This new disease entity connects seemingly unrelated conditions: systemic inflammatory syndromes (relapsing chondritis, Sweet's syndrome, and neutrophilic dermatosis) and hematologic disorders (myelodysplastic syndrome or multiple myeloma). Therefore, this article reviews the current literature on both disease entities.

VEXAS syndrome: a newly discovered systemic rheumatic disorder.

VEXAS syndrome is an adult-onset autoinflammatory disease associated with hematologic symptoms. The disease affects primarily males, and leads to death of a significant proportion of the patients. VEXAS syndrome is caused by a somatic mutation of the UBA1 gene in hematopoietic progenitor cells. The clinical picture of the syndrome consists of a number of organ manifestations including those akin to rheumatic diseases, arthritis, myalgia, vasculitis and chondritis.

Pulmonary manifestations in VEXAS syndrome.

BACKGROUND: Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome is a recently recognized multisystem disorder caused by somatic mutations in the UBA1 gene. METHODS: A retrospective cohort study was conducted on all patients with VEXAS syndrome evaluated at our institution from June 2020 through May 2022. Medical records and chest imaging studies were reviewed. RESULTS: We identified 45 subjects with median age of 68 years (range, 57-89), all men. Prior to VEXAS diagnosis, most patients had been diagnosed with various hematologic, rheumatologic, and dermatologic disorders. Most patients (84%) demonstrated canonical UBA1 methionine-41 (p.Met41) somatic mutations in hematopoietic cells. Fever (82%), skin lesions (91%), and respiratory symptoms (93%) were common presenting features. Chest CT manifested abnormalities in 91% of patients including parenchymal opacities in 25 (74%), most commonly ground-glass opacities (47%), along with mediastinal lymphadenopathy (29%), airway abnormalities (29%), and pleural effusion (24%). Pulmonary function test results available in 18 (40%) patients demonstrated mild restrictive impairment or normal results. Bronchoalveolar lavage and lung biopsy performed in a minority of patients demonstrated neutrophilic alveolitis and parenchymal inflammation, respectively. All patients received glucocorticoid therapy with at least partial response, but relapses were common and other immunosuppressive agents were employed in most patients. Pulmonary involvement appeared to improve in patients who received tocilizumab and JAK inhibitors. CONCLUSION: The pulmonary manifestations in VEXAS are relatively nonspecific and nonsevere, occur in the context of systemic inflammation and are responsive to escalation in glucocorticoid dosing.

A Pathogenic Missense Variant (c.1617G>A, p.Met539Ile) in UBA1 Causing Infantile X-Linked Spinal Muscular Atrophy (SMAX2).

Background: Infantile X-linked spinal muscular atrophy (SMAX2) is a rare type of spinal muscular atrophy associated with UBA1 variants. Methods: Clinical imaging and neurophysiological tests were performed on a Chinese patient with SMAX2. Further, focused panel sequencing of UBA1 was carried out on samples of both the proband and his maternal relatives. Results: The proband, a 4-year-old boy with the SMAX2 phenotype, suffered from reduced exercise capacity since infancy. His other symptoms included speech difficulties, severe nasal tone, reduced distal muscle strength, areflexia, and inadequate sucking ability. The brain MRI of the proband's showed normal results but the electromyography results showed multiple peripheral neurogenic lesions. Five male members of the proband's family were affected with the SMAX2 phenotype. They presented similar symptoms and had experienced a long and autonomous life. Molecular analysis revealed a novel missense variant (c.1617G>A, p.Met539Ile) in the exon 15 of UBA1. The proband's mother, as well as grandmother, carried the heterozygous missense UBA1 variant; whereas, the male patients from the family carried the hemizygotic variant. Conclusions: The affected members in this Chinese family showed unique features such as extended life span, no fractures, and cramps as compared with previously reported SMAX2 cases. The novel missense variant (c.1617G>A (p.Met539Ile) in UBA1 highlights the critical role of this gene in causing SMAX2 phenotype.

X-linked infantile spinal muscular atrophy (SMAX2) caused by novel c.1681G>A substitution in the UBA1 gene, expanding the phenotype.

X-linked infantile spinal muscular atrophy (SMAX2), OMIM 301830, is a rare, severe form of spinal muscular atrophy, caused by variants in the Ubiquitin like modifier-activating enzyme 1 (UBA1) gene. Clinical features reported to date include marked hypotonia, areflexia, arthrogryposis, contractures, myopathic facies and tongue fibrillations. Previous reports have included a history of contractures. We report a male patient presenting following a normal pregnancy with typical symptoms of X-linked infantile spinal muscular atrophy including hypotonia, weakness, areflexia and respiratory insufficiency, however contractures were absent. There was a significant family history of neuromuscular disease on the maternal side, with several male relatives all dying before the age of six months. Creatine Kinase was mildly elevated, MRI Brain was normal and neurophysiological testing revealed a diffuse motor neuronopathy. Genetic testing for SMN1 gene was normal. UBA1 sequencing revealed a maternally inherited hemizygous familial variant [c.1681G>A p. (Asp561Asn)], which has not been previously reported.

X-linked spinal muscular atrophy (SMAX2) caused by de novo c.1731C>T substitution in the UBA1 gene.

Infantile X-linked spinal muscular atrophy (SMAX2) is a rare form of spinal muscular atrophy manifesting as severe hypotonia, areflexia, arthrogryposis, facial weakness and cryptorchidism, and frequently accompanied by bone fractures. We present a male patient with SMAX2 who presented with typical symptoms at birth, preceded by reduced fetal movements in the second and third trimesters of pregnancy. Clinical examination revealed a myopathic face with a characteristic tent-shaped open mouth, tongue fibrillations, profound muscle weakness, areflexia, multiple contractures, mild skeletal abnormalities and cryptorchidism. In the first days of the patient's life, fractures of the right femur and right humerus were found; however, calcium-phosphate metabolism and densitometric examination were normal. Molecular analysis revealed a de novo c.1731C>T substitution in the UBA1 gene, which was localized in exon 15, the specific hot spot for mutation.