Brownstein, Catherine A.

Abstract Introduction: Erythromelalgia is a descriptive term for burning pain and erythema in distal extremities, often worsened by heat and improved by cold. Inherited erythromelalgia has been primarily linked to gain-of-function variants in SCN9A , encoding voltage-gated sodium channel NaV1.7. However, approximately 65% to 85% of patients with erythromelalgia do not have pathogenic SCN9A variants. Objectives: The objective of this study was to uncover and assess gene variants potentially associated with pediatric-onset erythromelalgia. Methods: With IRB approval and informed consent, probands and families with erythromelalgia underwent next-generation sequencing. A list of genes of interest was produced based on Mendelian inheritance models. Selected gene candidates were assessed using the Sequence Kernel Association Test-Optimal (SKAT-O). Results: Sixty-two probands with erythromelalgia and their relatives were included in Mendelian analysis, which identified variants in PR domain zinc finger protein 12 ( PRDM12 ) and dihydropyrimidinase-like protein 2 ( DPYSL2 ). In a targeted 12-gene rare-variant set analysis using SKAT-O, zinc finger homeobox protein 2 ( ZFHX2 ) showed evidence of association ( P = 6.9 × 10 −4 ), surpassing Bonferroni correction for 12 tests (α = 4.17 × 10 −3 ), whereas KIF1B showed only a nominal association signal ( P = 0.03) that did not survive multiple-testing correction. Conclusion: Genes associated with both increased and decreased pain sensitivity are of considerable interest for elucidating pain mechanisms and analgesic development. As rare variants in PRDM12 and DPYSL2 were identified in a pediatric erythromelalgia cohort and a gene-based rare-variant association signal for ZFHX2 was identified, replication and functional validation are needed.

Background/Objectives: Erythromelalgia is a rare condition characterized by burning pain, redness, and warmth primarily in the extremities, usually worsened by heat and alleviated by cold. The objective of this study was to identify the top 10 priorities in pediatric erythromelalgia from multiple perspectives, including clinicians, people with lived experience of childhood-onset erythromelalgia, and their family members. Methods: A modified James Lind Alliance Priority-Setting Process was conducted. The top priorities were identified through four phases: (1) an international online survey to gather priorities, (2) data processing, (3) an interim prioritization online survey, and (4) a virtual workshop to set the final priorities. Results: In phase 1, 185 potential priorities were submitted by 74 respondents (53% patients, 24% family members, and 23% clinicians) that were developed into 68 unique research questions (phase 2). In phase 3, of the 68 questions, 50 were rated for importance by 58 participants (38% patients, 36% family members, and 26% clinicians), reducing the list to 25 questions. In phase 4, the top 10 was reached through consensus by 12 participants (33% patients, 25% family members, and 42% clinicians) across Canada, South Africa, the United States of America, and the United Kingdom. Conclusions: The final priorities focused on the treatment of erythromelalgia, understanding underlying mechanisms, the association of erythromelalgia with various body systems, and generating awareness. This list is the first international patient-centered research agenda for childhood-onset erythromelalgia and a call to action from key partners to improve future research and care.

Significance By evaluating children with a malformed cerebral cortex, we identified an ATPase pump (ATP1A3) with an early role in brain development. The ATP1A3 pump maintains the physiological concentration of sodium and potassium ions in cells, a process critical for osmotic equilibrium and membrane potential across several developing cell populations. We employed single-cell sequencing approaches to identify key enrichments for ATP1A3 expression during human cortex development. Unravelling this early cell-type–specific pathophysiology in the developing brain offers a potential basis for the treatment of ATP1A3 -related diseases affecting prenatal and early childhood development.