Workflow for Management of Gonadal Neoplasm in 2 Patients with Differences of Sex Development Enrolled in an Experimental Gonadal Tissue Cryopreservation Protocol.

OBJECTIVE: To outline our experimental gonadal tissue cryopreservation (GTC) protocol that does not disrupt the standard of care in medically-indicated gonadectomy for patients with differences of sex development, including highlighting the multidisciplinary collaborative protocol for when neoplasm is discovered in these cases. METHODS: Two patients with complete gonadal dysgenesis who were undergoing medically-indicated prophylactic bilateral gonadectomy elected to pursue GTC. Both were found to have germ cell neoplasia in situ on initial pathologic analysis, requiring recall of the gonadal tissue, which had been cryopreserved. RESULTS: Cryopreserved gonadal tissue was successfully thawed and transferred to pathology for complete analysis. No germ cells were identified in either patient nor were found to have malignancy, so further treatment beyond gonadectomy was not indicated. Pathologic information was communicated to each family, including that long-term GTC was no longer possible. CONCLUSION: Organizational planning and coordination between the clinical care teams, GTC laboratory, and pathology were key to handling these cases with neoplasia. Processes that anticipated the possibility of discovering neoplasia within tissue sent to pathology and the potential need to recall GTC tissue to complete staging included (1) documenting the orientation and anatomical position of tissue processed for GTC, (2) defining parameters in which tissue will be recalled, (3) efficiently thawing and transferring GTC tissue to pathology, and (4) coordinating release of pathology results with verbal communication from the clinician to provide context. GTC is desired by many families and at the time of gonadectomy and is (1) feasible for patients with DSD, and (2) did not inhibit patient care in 2 patients with GCNIS.

Novel genetically engineered H3.3G34R model reveals cooperation with ATRX loss in upregulation of Hoxa cluster genes and promotion of neuronal lineage.

Background: Pediatric high-grade gliomas (pHGGs) are aggressive pediatric CNS tumors and an important subset are characterized by mutations in H3F3A, the gene that encodes Histone H3.3 (H3.3). Substitution of Glycine at position 34 of H3.3 with either Arginine or Valine (H3.3G34R/V), was recently described and characterized in a large cohort of pHGG samples as occurring in 5-20% of pHGGs. Attempts to study the mechanism of H3.3G34R have proven difficult due to the lack of knowledge regarding the cell-of-origin and the requirement for co-occurring mutations for model development. We sought to develop a biologically relevant animal model of pHGG to probe the downstream effects of the H3.3G34R mutation in the context of vital co-occurring mutations. Methods: We developed a genetically engineered mouse model (GEMM) that incorporates PDGF-A activation, TP53 loss and the H3.3G34R mutation both in the presence and loss of Alpha thalassemia/mental retardation syndrome X-linked (ATRX), which is commonly mutated in H3.3G34 mutant pHGGs. Results: We demonstrated that ATRX loss significantly increases tumor latency in the absence of H3.3G34R and inhibits ependymal differentiation in the presence of H3.3G34R. Transcriptomic analysis revealed that ATRX loss in the context of H3.3G34R upregulates Hoxa cluster genes. We also found that the H3.3G34R overexpression leads to enrichment of neuronal markers but only in the context of ATRX loss. Conclusions: This study proposes a mechanism in which ATRX loss is the major contributor to many key transcriptomic changes in H3.3G34R pHGGs. Accession number: GSE197988.