Clinical Characteristics

COQ2 defects are associated with a wide clinical spectrum, including kidney disease, central nervous system symptoms and visual impairment. Age of onset varies from the neonatal period up to the seventh decade of life.

The main clinical pictures that have been associated with COQ2 mutations include:

  1. A severe disease that is rapidly progressive, involves multiple organs (central nervous system, kidney, heart, liver, lung). This condition usually manifests in the first days of life, show very limited response to treatment and rapidly evolves to multiorgan failure.
  2. In other patients the disease appears later in life with a renal disease as the main manifestation. The first symptom is proteinuria (increased proteins in the urine), which starts usually in childhood, or more rarely in adolescence, which, if untreated, evolves to steroid-resistant nephrotic syndrome (SRNS), a disease affecting the glomerulus that does not respond to standard steroid therapy. Kidney involvement in some patients may be accompanied by neurological symptoms (seizures, developmental delay, dystonia, nystagmus) and visual impairment consequent to a retinal or optic nerve problem.
  3. Few patients manifest later in life (in the 6°-7° decade) a neurological disease (with tremor, slow movement, postural instability, ataxia) associated with retinopathy.