A case with febrile attacks and vasculopathy associated with ADA2 and MEFV pathogenic variants

Deficiency of adenosine deaminase 2 (DADA2), caused by recessive mutations in the adenosine deaminase 2 (ADA2) gene, results in cutaneous or systemic vasculitis with variable clinical manifestations. There is only one other case in literature carrying both ADA2 and MEFV gene pathogenic variants. Here we report the second case that carries both ADA2 and MEFV pathogenic variants, presenting with characteristic phenotypes of both familial Mediterranean fever (FMF) and DADA2. A male patient, currently 29 years old, was initially diagnosed with FMF and developed livedo reticularis and nodular dermal lesions compatible with cutaneous polyarteritis nodosa (PAN) a year after diagnosis. His family history revealed a brother 2 years older than himself who was diagnosed with PAN and died at age 22 because of gut perforation secondary to acute mesenteric ischaemia. ADA2 gene mutation analysis on chromosome 22q11.1 was positive, and the patient responded to colchicine and infliximab.

How I diagnose myeloid neoplasms with germline predisposition

OBJECTIVES

Pathologists play a crucial role in the initial diagnosis of germline predisposition to myeloid neoplasia and subsequent surveillance for disease progression. The diagnostic workup can be challenging, particularly if clinical history, laboratory testing, or genetic studies are incomplete or unavailable.

METHODS

Through case-based examples, we illustrate common diagnostic challenges and pitfalls encountered during bone marrow examination of patients being evaluated for myeloid malignancy with potential germline predisposition to myeloid neoplasia.

RESULTS

Lack of familial disease, the absence of syndromic manifestations, and late-onset hematologic malignancy do not exclude an underlying germline predisposition syndrome. Targeted myeloid sequencing panels can help identify potential germline alterations but may not detect large deletions or insertions, noncoding, or novel variants. Confirmation of the germline nature of an alteration detected in the peripheral blood or bone marrow ideally requires genetic testing using nonhematopoietic germline DNA to definitively distinguish between germline and somatic alterations. The ideal tissue source for germline testing is cultured skin fibroblasts. Certain germline predisposition syndromes can contain characteristic baseline bone marrow dysplastic-appearing features associated with cytopenias without constituting myelodysplastic syndrome.

CONCLUSION

Recognizing germline predisposition to myeloid neoplasia is critical for proper disease management. This recognition is particularly important for patients who will undergo hematopoietic stem cell transplantation to screen potential related donors. Integration of the clinical history, bone marrow findings, cytogenetic studies, and specialized laboratory and molecular genetic testing is often essential for accurate diagnosis and subsequent disease monitoring.