[1] Univ Autonoma Nuevo Leon, Hosp Univ Dr Jose Eleuterio Gonzalez, Monterrey, Nuevo Leon, Mexico
[2] Univ Veracruzana, Lab Fisiol Digest & Motilidad Gastrointestinal, Inst Invest Med Biol, Xalapa, Veracruz, Mexico
[3] Ctr Med ISSEMYM, Metepec, Estado De Mexic, Mexico
[4] Univ Nueva York, Escuela Med, New York, NY USA
[5] IMSS, UMAE Hosp Pediat Dr Silvestre Frenck Freud, CMN Siglo 21, Mexico City, DF, Mexico
[6] Hosp Angeles Acoxpa, Mexico City, DF, Mexico
[7] Hosp Atenc Med Ambulatoria UAG, Guadalajara, Jalisco, Mexico
[8] Div Epidemiol & Genet Canc, Ockville, MD USA
[9] Inst Nacl Canc, Ockville, MD USA
[10] Hosp Gen Miguel Silva, Morelia, Michoacan, Mexico
[11] Inst Nacl Cancerol, Dept Endoscopia, Mexico City, DF, Mexico
[12] Inst Nacl Cancerol, Dept Patol, Mexico City, DF, Mexico
[13] Hosp Angeles Torreon, Torreon, Coahuila, Mexico
[14] IMSS, UIMY, Unidad Med Alta Especialidad Merida, Merida, Yucatan, Mexico
[15] IMSS, Direcc Educ & Invest Salud, UMAE Hosp Especialidades, Ctr Med Nacl Manuel Avila Camacho, Puebla, Mexico
[16] IMSS, Hosp Especialidades Dr Bernardo Sepulveda, CMN Siglo 21, Mexico City, DF, Mexico
[17] Pontificia Univ Catolica Chile, Fac Med, Dept Ciencias Salud, Santiago, Chile
[18] Univ Veracruzana, Inst Salud Publ, Xalapa, Veracruz, Mexico
[19] Inst Nacl Ciencias Med & Nutr Salvador Zubiran, Dept Gastroenterol, Mexico City, DF, Mexico
[20] Inst Nacl Ciencias Med & Nutr Salvador Zubiran, Lab Motilidad Gastrointestinal, Mexico City, DF, Mexico
[21] Hosp Civil Guadalajara, Guadalajara, Jalisco, Mexico