El sindrome de Marfan (MFS) es la enfermedad del tejido conectivo mas comun de origen genetico, con transmision hereditaria autosomica dominante. La mutacion se localiza en el gen FBN1 que codifica para la proteina Fibrilina-1. Las principales manifestaciones son: dilatacion de la aorta ascendente, diseccion aortica, ectasia dural lumbosacra, pectus carinatum, ectopia lentis. Se reporta un caso de MFS tipo 1 con importante pectus carinatum. En el servicio de genetica humana del Laboratorio de Investigaciones de la Universidad de Cartagena se recibio un paciente masculino de 26 anos asintomatico. Los sonidos Korotkoff estaban ausentes en el brazo derecho. Se encontro dolicostenomelia, aracnodactilia, pectus carino-excavatum y subluxacion bilateral del cristalino. Los signos de Gowers y Walker-Murdoch fueron positivos. El MFS se diagnostica segun la nosologia de Ghent. Las alteraciones musculoesqueleticas y la ectopia lentis cumplen dos de los criterios mayores. La historia familiar de aneurisma aortico y otras manifestaciones clinicas sugieren una aproximacion diagnostica en este paciente. Se requiere asesoria genetica para prevenir la morbilidad y la mortalidad prematura en los descendientes. Rev.cienc.biomed.2011; 2 (2): 305-310 PALABRAS CLAVE Sindrome de Marfan. Aracnodactilia. Torax en embudo. Aneurisma de la aorta SUMMARY Marfan syndrome (MFS) is the most common connective tissue inherited disorder, transmitted as an autosomic dominant character. Mutation is located in FBN1 allele, that encodes to Fibrilin-1. Dilation of ascending aorta, aortic dissection, lumbosacral dural ectasia, pectus carinatum and ectopia lentis are the major manifestations. A MFS type 1 with notorious pectus carinatum is reported. A 26 years old male was received to human genetics service, in absence of acute symptoms. Korotkoff sounds were absented in right arm. Dolichostenomelia, arachnodactyly and pectus carinoexcavatum and bilateral lens subluxation were found. Gowers sign and Walker-Murdoch sign were positive. MFS was diagnostic according to Ghent’s nosology. Musculoeskeletal alterations and lens ectopia full filled two major criteria. Parents’ history of aortic aneurysm and clinical manifestation suggest a preventive approach to this patient. Also genetic counseling is required in order to reduce morbidity and premature mortality in offspring. Rev.cienc.biomed.2011; 2 (2): 305-310 KEYWORDS Marfan Syndrome. Arachnodactyly. Funnel chest. Aortic aneurysm.