Lowe syndrome - Old and new evidence of secondary mitochondrial dysfunction

Abstract

The oculocerebrorenal syndrome of Lowe (LS) is a rare, progressive, multisystemic X-linked disorder caused by mutations in OCRL gene. Patients classically present with ocular abnormalities including bilateral congenital cataracts and glaucoma, intellectual delay, severe generalized hypotonia with absent tendon reflexes, and proximal renal tubular dysfunction. Congenital bilateral cataracts and hypotonia are present at birth in almost all patients, while other classical symptoms develop gradually with variable severity. Consequently, differential diagnosis in infant period in these patients can be broad including other rare metabolic and neurologic disorders. Herein we present a 4.5 year old boy with Lowe syndrome caused by mutation of OCRL gene, NM_000276.4:c.643C > T; p.(Gln215*), initially diagnosed as having mitochondriopathy due to alteration of mitochondria on electron microscopic examination in different tissues and decreased values of mitochondrial energy metabolism measurements in muscle. No pathogenic mutations in mitochondrial DNA were found on whole exome sequencing. This patient recall historical hypothesis of secondary mitochondrial dysfunction in Lowe syndrome, that may be caused/intensified by some of disease symptoms.

Keywords: Lowe syndrome; Mitochondriopathy; OCRL gene; Oculocerebrorenal syndrome.