APOE encodes a protein that carries lipids between cells. The familiar APOE e2, e3 and e4 groupings depend on the combination of rs429358 and rs7412, not on either marker read in isolation.
NTRK2 encodes TrkB, a receptor involved in responding to neurotrophic signals such as BDNF. These signals support nervous-system function and plasticity. NTRK2 is not a phosphatidylserine absorption transporter.