The Marfan sindrome is caused by an autosomal dominant allele. The location of the defective gene seems to be the 15th chromosome. Being a dominant allele, it means that the child might be affected only if one of the parents has the disease (meaning that it has the gene). If one of the parents is monozygous for the defective gene, the probability for the descendants to inherit the trait is 100%. If the parent is heterozygous, then the chances are 50%. If both parents are heterozygous, the chances are 75%. Marfan sindrome is a disease of the connective tissue. The most important complications are eye problems (the crystalin is displaced) and heart problems, which may lead to heart failure and eventually death.