Rationale:
E.M., a 26 year old woman, began experiencing episodic appendicular and axial myoclonus at the age of 18. Her symptoms progressively worsened, and she also developed generalized tonic-clonic seizures (GTCS) with photosensitivity. Neurologic examination revealed an ataxic gait, dysmetria and dysarthria. Regarding her family history, the patient has six siblings, with one of them affected by the same disease. Electroencephalography showed normal baseline activity and Waltz 3 type photoparoxysmal response. The patient's brain magnetic resonance imaging (MRI) revealed discrete cerebral atrophy, while laboratory exams showed normal renal function.Epilepsy genetic panel showed homozygous mutation of the SCARB2 gene.
Methods: We present a case report documenting the clinical findings and genetic analysis of E.M., who was diagnosed with progressive myoclonic epilepsy (PME). PME encompasses a group of inherited neurodegenerative diseases characterized by myoclonia, pharmacoresistant epileptic seizures, varying degrees of neurological dysfunction, progressive evolution, and a severe prognosis. Recently, a rare type of PME known as Actin Myoclonus - Renal Failure (AMRF) Syndrome has been attributed to mutations in the SCARB2 gene. This form of PME follows an autosomal recessive inheritance pattern and presents with action myoclonus, dysarthria, ataxia, GTCS, intellectual deficit, and, in some cases, kidney dysfunction.
Results: Our findings confirm that E.M. has AMRF syndrome, caused by a homozygous mutation of the SCARB2 gene. To the best of our knowledge, this is the first reported case of AMRF syndrome in Brazil.
Conclusions: This case report contributes to the understanding of AMRF syndrome, a rare form of PME, and its presence among indigenous communities in Brazil. It is crucial to expand the differential diagnosis of PME to include this rare subtype and emphasize the importance of appropriate genetic testing.
Funding: FAPESC-PRONEM TO 2020TR736