IDH-Mutant Astrocytoma With Chromosome 19q13 Deletion Manifesting as an Oligodendroglioma-Like Morphology.

Partial deletions in chromosomes 1p and 19q are found in a subset of astrocytic tumors; however, it remains unclear how these alterations affect their histological features and prognosis. Herein, we present 3 cases of isocitrate dehydrogenase (IDH)-mutant astrocytoma with chromosome 19q13 deletion. In the first case, the primary tumor harbored an IDH1 mutation with chromosome 1p/19q partial deletions, which covered 19q13 and exhibited a durable initial response to radiotherapy and temozolomide (TMZ) treatment. However, the tumor lost the chromosome 1p/19q partial deletions at recurrence and became resistant to TMZ. Histologically, an oligodendroglioma-like feature was found in the primary tumor but not in the recurrent tumor. Capicua transcriptional repressor (CIC), located on 19q13, was less expressed in the primary tumor but was highly expressed in the recurrent tumor. Similar histological findings were observed in 2 other astrocytic tumors with IDH1 or IDH2 mutations. These tumors also had chromosome 19q13 deletion, including the CIC gene, weakly expressed CIC, and oligodendroglioma-like morphology. These tumors recurred at 6 and 32 months, respectively. These findings suggest that IDH-mutant astrocytoma with chromosome 19q13 partial deletion, including the CIC gene, may induce an oligodendroglioma-like phenotype, but the clinical prognosis may not be similar to that of genetically defined oligodendroglioma.

[A Case of Primary Central Nervous System Lymphoma Originated from Optic Chiasma and Presenting Difficulty in Diagnosis].

We report a case of primary central nervous system lymphoma(PCNSL)originating from an optic chiasma, which was difficult to diagnose but was finally diagnosed by biopsy. A 62-year-old immunocompetent man presented with bilateral visual field disturbance, hypopituitarism, and diabetes insipidus;an optic chiasm lesion was detected on MRI. After starting steroid supplementation for adrenal insufficiency, visual field disturbance immediately improved. Since the lesion completely disappeared three months after its onset, it became the follow-up without histological confirmation. Six months after the onset, visual field disturbance progressed, and the lesion recurred. We performed a left optic nerve biopsy to maintain the right visual field, which remained partially. The pathology was PCNSL. We performed postoperative chemoradiotherapy, and the patient showed remission and improvement of the visual field. Isolated PCNSLs arising from optic chiasma are very rare. The diagnosis of optic chiasm lesions is difficult due to their similarity with a variety of inflammatory/autoimmune disease and neoplastic lesions. When a lymphoma is considered to be differentiated, early biopsy should be performed before administering a steroid. The approach and sampling site to prevent the function are also important for biopsy.

[A mouse model with human chromosomal abnormality observed in autism].

Substantial evidence suggests that chromosomal abnormalities contribute to the risk of autism. The duplication of human chromosome 15q11-q13 is known to be the most frequent cytogenetic abnormality observed in autism. We replicate this genetic abnormality in mice by using chromosome engineering to generate a 6.3 Mb duplication of the conserved linkage group on mouse chromosome 7. Mice with paternal duplication showed poor social interaction, behavioral inflexibility, abnormal ultrasonic vocalizations, and correlates of anxiety. This chromosome-engineered mouse model for autism seems to replicate various aspects of human autistic phenotypes and validates the relevance of the human chromosomal abnormality. This model will help in understanding the genetics of developmental brain disorders and thereby serve as an invaluable tool for therapeutic development.