PIK3R5 and Ataxia with vitamin E deficiency: For example, low vitamin E levels are suggestive of ATX-TTPA (ataxia with vitamin E deficiency, AVED) and abetalipoproteinemia (MTTP), whilst elevated alpha-fetoprotein (AFP) is seen in ATX-ATM (ataxia telangiectasia, AT), with milder/variable elevations also seen in ATX-APTX (ataxia-oculomotor apraxia type 1, AOA1), ATX-SETX (AOA2), ATX-PIK3R5 (AOA3), and rarely in ATX-ANO10 (ARCA3)[87–90].