Serum triglyceride level =< 300 mg/dL (=< 3.42 mmol/L)Xx_NEWLINE_xXSerum triglyceride =< 300 mg/dL (applicable only for dose levels that include isotretinoin) (note that a non-fasting triglyceride value could be obtained, if this is > 300 mg/dL then a fasting triglyceride should be obtained and patient will be eligible if the fasting level is =< 300 mg/dL)Xx_NEWLINE_xXFasting triglyceride =< 2.5 x ULNXx_NEWLINE_xXFasting triglyceride =< 200 mg/dL; ONLY APPLICABLE for patients with NF2 mutation (GSK2256098)Xx_NEWLINE_xXSerum triglyceride level =< 300 mg/dLXx_NEWLINE_xXSerum triglyceride level =< 300 mg/dL within 7 days prior to enrollmentXx_NEWLINE_xX