Pearls & Oy-sters: Adult-Onset Coats Plus

Coats plus (Cp) is a pleiotropic disorder with multisystemic manifestations including retinal vascular disease and leukoencephalopathy with intracranial calcifications and cysts. It is an autosomal recessive telomere biology disorder mostly associated with compound heterozygous defects in <i>CTC1</i> gene. Cp typically presents in early childhood with poor long-term prognosis. In this study, we describe the case of a 46-year-old woman presenting with a first unprovoked seizure in the setting of 2 years of progressive behavioral and cognitive deterioration. Her medical history was notable for retinal vascular disease, anemia, restrictive lung disease under consideration for transplantation, osteoporosis, and infertility, with persistently elevated antinuclear antibodies concerning for a possible systemic autoimmune disease. She had been treated with chronic immunosuppression for the previous 9 years without a clear response, although with poor compliance. Her family history was unremarkable. Brain MRI revealed an asymmetric leukoencephalopathy with a gadolinium-enhancing tumefactive lesion and intracranial calcifications. Acquired etiologies such as malignancy, inflammatory, and infectious diseases were excluded. Despite adult onset, absence of family history, and asymmetrical MRI brain findings, we then considered a genetic autoinflammatory or neurovascular syndrome. Sanger sequencing of the <i>TREX1</i> gene excluded retinal vasculopathy with leukoencephalopathy and systemic manifestations (RVCL-S). A large multigene panel for neurologic diseases identified a homozygous pathogenic in-frame deletion in the <i>CTC1</i> gene (NM_025099.6:c.2954_2956del), establishing the diagnosis of Cp. This case broadens the clinical spectrum of Cp to include a milder adult-onset phenotype. Moreover, it highlights Cp as a potential mimic of autoimmunity, with the need to question previously presumed diagnoses.