Equity in action: The Diagnostic Working Group of The Undiagnosed Diseases Network International.

Rare diseases are recognized as a global public health priority. A timely and accurate diagnosis is a critical enabler for precise and personalized health care. However, barriers to rare disease diagnoses are especially steep for those from historically underserved communities, including low- and middle-income countries. The Undiagnosed Diseases Network International (UDNI) was launched in 2015 to help fill the knowledge gaps that impede diagnosis for rare diseases, and to foster the translation of research into medical practice, aided by active patient involvement. To better pursue these goals, in 2021 the UDNI established the Diagnostic Working Group of the UDNI (UDNI DWG) as a community of practice that would (a) accelerate diagnoses for more families; (b) support and share knowledge and skills by developing Undiagnosed Diseases Programs, particularly those in lower resource areas; and (c) promote discovery and expand global medical knowledge. This Perspectives article documents the initial establishment and iterative co-design of the UDNI DWG.

Occurrence of cancer in Marfan syndrome: Report of two patients with neuroblastoma and review of the literature.

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder caused by pathogenic variants in FBN1, with a hitherto unknown association with cancer. Here, we present two females with MFS who developed pediatric neuroblastoma. Patient 1 presented with neonatal MFS and developed an adrenal neuroblastoma with unfavorable tumor genetics at 10 months of age. Whole genome sequencing revealed a germline de novo missense FBN1 variant (NP_000129.3:p.(Asp1322Asn)), resulting in intron 32 inclusion and exon 32 retention. Patient 2 was diagnosed with classic MFS, caused by a germline de novo frameshift variant in FBN1 (NP_000129.3:p.(Cys805Ter)). At 18 years, she developed high-risk neuroblastoma with a somatic ALK pathogenic variant (NP_004295.2:p.(Arg1275Gln)). We identified 32 reported cases of MFS with cancer in PubMed, yet none with neuroblastoma. Among patients, we observed an early cancer onset and high frequency of MFS complications. We also queried cancer databases for somatic FBN1 variants, finding 49 alterations reported in PeCan, and variants in 2% of patients in cBioPortal. In conclusion, we report the first two patients with MFS and neuroblastoma and highlight an early age at cancer diagnosis in reported patients with MFS. Further epidemiological and functional studies are needed to clarify the growing evidence linking MFS and cancer.

Uncommon Variants in FLG2 and NOD2 Are Associated with Atopic Dermatitis in the Ethiopian Population.

Loss-of-function variants in the FLG gene have been identified as the strongest cause of susceptibility to atopic dermatitis (AD) in Europeans and Asians. However, very little is known about the genetic etiology behind AD in African populations, where the prevalence of AD is notably high. We sought to investigate the genetic origins of AD by performing whole-genome sequencing in an Ethiopian family with 12 individuals and several affected in different generations. We identified 2 variants within FLG2 (p.D13Y) and NOD2 (p.A918S) genes cosegregating with AD in the affected individuals. Further genotyping analyses in both Ethiopian and Swedish AD cases and controls revealed a significant association with the FLG2 variant (p.D13Y, P < .0013) only in the Ethiopian cohort. However, the NOD2 variant (p.A918S) did not show any association in our Ethiopian cohort. Instead, 2 previously recognized NOD2 variants (p.A849V, P < .0085 and p.G908R, P < .0036) were significantly associated with AD in our Ethiopian cohort. Our study indicates that the FLG2 and NOD2 genes might be important in the etiology of AD in Ethiopians. Additional genetic and functional studies are needed to confirm the role of these genes and the associated variants into the development of AD.

Diagnostic yield and clinical impact of germline sequencing in children with CNS and extracranial solid tumors-a nationwide, prospective Swedish study.

Background: Childhood cancer predisposition (ChiCaP) syndromes are increasingly recognized as contributing factors to childhood cancer development. Yet, due to variable availability of germline testing, many children with ChiCaP might go undetected today. We report results from the nationwide and prospective ChiCaP study that investigated diagnostic yield and clinical impact of integrating germline whole-genome sequencing (gWGS) with tumor sequencing and systematic phenotyping in children with solid tumors. Methods: gWGS was performed in 309 children at diagnosis of CNS (n = 123, 40%) or extracranial (n = 186, 60%) solid tumors and analyzed for disease-causing variants in 189 known cancer predisposing genes. Tumor sequencing data were available for 74% (227/309) of patients. In addition, a standardized clinical assessment for underlying predisposition was performed in 95% (293/309) of patients. Findings: The prevalence of ChiCaP diagnoses was 11% (35/309), of which 69% (24/35) were unknown at inclusion (diagnostic yield 8%, 24/298). A second-hit and/or relevant mutational signature was observed in 19/21 (90%) tumors with informative data. ChiCaP diagnoses were more prevalent among patients with retinoblastomas (50%, 6/12) and high-grade astrocytomas (37%, 6/16), and in those with non-cancer related features (23%, 20/88), and ≥2 positive ChiCaP criteria (28%, 22/79). ChiCaP diagnoses were autosomal dominant in 80% (28/35) of patients, yet confirmed de novo in 64% (18/28). The 35 ChiCaP findings resulted in tailored surveillance (86%, 30/35) and treatment recommendations (31%, 11/35). Interpretation: Overall, our results demonstrate that systematic phenotyping, combined with genomics-based diagnostics of ChiCaP in children with solid tumors is feasible in large-scale clinical practice and critically guides personalized care in a sizable proportion of patients. Funding: The study was supported by the Swedish Childhood Cancer Fund and the Ministry of Health and Social Affairs.

Rare coding variants in NOX4 link high ROS levels to psoriatic arthritis mutilans.

Psoriatic arthritis mutilans (PAM) is the rarest and most severe form of psoriatic arthritis, characterized by erosions of the small joints and osteolysis leading to joint disruption. Despite its severity, the underlying mechanisms are unknown, and no susceptibility genes have hitherto been identified. We aimed to investigate the genetic basis of PAM by performing massive parallel sequencing in sixty-one patients from the PAM Nordic cohort. We found rare variants in the NADPH oxidase 4 (NOX4) in four patients. In silico predictions show that the identified variants are potentially damaging. NOXs are the only enzymes producing reactive oxygen species (ROS). NOX4 is specifically involved in the differentiation of osteoclasts, the cells implicated in bone resorption. Functional follow-up studies using cell culture, zebrafish models, and measurement of ROS in patients uncovered that these NOX4 variants increase ROS levels both in vitro and in vivo. We propose NOX4 as the first candidate susceptibility gene for PAM. Our study links high levels of ROS caused by NOX4 variants to the development of PAM, offering a potential therapeutic target.