Overlapping Diseases in a Brazilian Subject with Brain Calcification Linked to Novel Phenotypes

Abstract

Primary familial brain calcification (PFBC) is a well-known genetic condition that has recently had a surge of autosomal recessive cases. We recently reported a case of autosomal recessive PFBC on a 54-year-old Brazilian patient with a novel homozygous variant on MYORG. Interestingly, that patient also had a series of uncommon signs and symptoms, including Hashimoto's thyroiditis, polyneuropathy, optic nerve head drusen (ONHD), and persistent anemia. We chose to perform whole exome sequencing (WES) to possibly detect other unknown genetic conditions that could explain the extra-neurological findings reported. WES confirmed the presence of the MYORG variant previously reported by us, and determined the presence of a heterozygous nonsense variant on HBB (c.118C > T, p.Q40*), defining a diagnosis of beta-thalassemia. Based on literature review, the new WES finding explains the persistent anemia and polyneuropathy shown by the patient, while still leaving the ONHD and autoimmune thyroiditis without a clear genetic link. This way, we propose that these novel clinical findings could be linked to MYORG, but still encourage further studies to evaluate this possibility.

Keywords: Drusen; MYORG; Primary familial brain calcification; Thalassemia; Whole exome sequencing.