What is the genetic disorder progeria caused by? Is it a simple recessive trait?

Two likely forms. Progeria syndrome is considered a sporadic (new mutation) phenomenon that has few prenatal indicators. At an average birth wt of 6lb (2.7kg), the relatively small size during gestation is not specific to this disorder. There are rare instances of siblings to normal parents, showing that an autosomal recessive form exists.Most begin to show signs by 6-18mo.