gray matter heterotopia; left arm was red & hot & it hurt; shaking with her arms fully extended down the sides of her body; seizure lasted 30 seconds/shaking with her arms fully extended down the sides of her body; bruise on her back the size of the index finger; couldn't get off the bed; It felt like something was holding her down; her left arm hurt; left arm was red & hot & it hurt/injection site then was red and sand dollar sized; left arm was red & hot & it hurt/injection site then was red and sand dollar sized; her left arm & left upper back hurt; This spontaneous case was reported by a consumer and describes the occurrence of SEIZURE (seizure lasted 30 seconds/shaking with her arms fully extended down the sides of her body) and GREY MATTER HETEROTOPIA (gray matter heterotopia) in a 21-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 001B21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Agenesis of clavicle congenital (agenesis of the corpus collosum & hypopituitarism). Concurrent medical conditions included Hypopituitarism.    On 17-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 17-Mar-2021, the patient experienced FATIGUE (couldn't get off the bed; It felt like something was holding her down), PAIN IN EXTREMITY (her left arm hurt), BACK PAIN (her left arm & left upper back hurt), VACCINATION SITE ERYTHEMA (left arm was red & hot & it hurt/injection site then was red and sand dollar sized) and VACCINATION SITE SWELLING (left arm was red & hot & it hurt/injection site then was red and sand dollar sized). On 18-Mar-2021, the patient experienced SEIZURE (seizure lasted 30 seconds/shaking with her arms fully extended down the sides of her body) (seriousness criterion medically significant), CONTUSION (bruise on her back the size of the index finger) and TREMOR (shaking with her arms fully extended down the sides of her body). On an unknown date, the patient experienced GREY MATTER HETEROTOPIA (gray matter heterotopia) (seriousness criterion medically significant) and PERIPHERAL SWELLING (left arm was red & hot & it hurt). At the time of the report, SEIZURE (seizure lasted 30 seconds/shaking with her arms fully extended down the sides of her body), GREY MATTER HETEROTOPIA (gray matter heterotopia), FATIGUE (couldn't get off the bed; It felt like something was holding her down), PAIN IN EXTREMITY (her left arm hurt), CONTUSION (bruise on her back the size of the index finger), PERIPHERAL SWELLING (left arm was red & hot & it hurt), BACK PAIN (her left arm & left upper back hurt), TREMOR (shaking with her arms fully extended down the sides of her body), VACCINATION SITE ERYTHEMA (left arm was red & hot & it hurt/injection site then was red and sand dollar sized) and VACCINATION SITE SWELLING (left arm was red & hot & it hurt/injection site then was red and sand dollar sized) outcome was unknown.        The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   patient had MRI  which found  was predisposed to seizures due to gray matter heterotopia. No concomitant medications were provided by the reporter. patient treatment information was hormones and Cortisol.  This case concerns a 21-year-old, female patient with previous relevant medical history of agenesis of the corpus collosum and hypopituitarism, who experienced the unexpected events of seizure and grey matter heterotopia. The events occurred the same day after the first dose of mRNA-1273. The rechallenge was unknown since no information about the outcome of the events was disclosed. The medical history of agenesis of the corpus collosum and hypopituitarism  remains a confounder. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This case concerns a 21-year-old, female patient with previous relevant medical history of agenesis of the corpus collosum and hypopituitarism, who experienced the unexpected events of seizure and grey matter heterotopia. The events occurred the same day after the first dose of mRNA-1273. The rechallenge was unknown since no information about the outcome of the events was disclosed. The medical history of agenesis of the corpus collosum and hypopituitarism  remains a confounder. The benefit-risk relationship of mRNA-1273 is not affected by this report.