Case of Mitochondrial Encephalomyopathy secondary to COVID-19 in a Pediatric case of SIFD syndrome with a novel TRNT1 mutation

Syndrome of Congenital Sideroblastic Anemia, B-cell Immunodeficiency, Periodic Fevers, and Developmental Delay (SIFD) is caused by mutations in the tRNA nucleotidyltransferase 1 (TRNT1) gene. We present the case of a 13-month-old boy with developmental delay, microcytic anemia, and recurrent febrile illnesses. Immunological workup revealed B cell lymphopenia. Whole exome sequencing identified two novel heterozygous mutations in the TRNT1 gene (Thr49Fs and Ile122Thr). Our patient had a milder phenotype than previously reported cases of sideroblastic anemia. However, he developed left ventricular dilated cardiomyopathy at the age of 2 years. At the age of 5 years, COVID-19 infection resulted in mitochondrial encephalomyopathy and respiratory failure. Subsequent immunology evaluation revealed low IgG levels, prompting the initiation of immunoglobulin replacement therapy. This case highlights the importance of genetic testing in multisystem disorders and the variable clinical course in SIFD patients. Additionally, it emphasizes the unique susceptibility to COVID-19 due to immunodeficiency and mitochondrial defects.