Chromosomal region 13q21q31 and heterochrony of development.

If the theory of evolution is now largely accepted, there are still many debates on the mechanisms of evolution, including human evolution. One of these mechanisms is heterochrony of development including progenesis and neoteny. We report on a patient who could be an example of human progenesis. This boy was born prematurely, after a cesarian section for preeclampsia. Family history was unremarkable. He walked unaided when he was 2.5 years old. At 5 years of age height was 95 cm (< 3rd centile), weight 18.6 kg (40th centile) and OFC 54 cm (98th centile is 53 cm). He had a macropenis. He attended elementary school. However, at 9 years of age he had to have special education. Puberty occurred when he was 8 years old. At 14 years of age height was 141 cm (3rd centile is 144 cm), weight 32.5 kg (3rd centile) and OFC 55.5 cm (75th centile). At physical examination he had hypertelorism, narrow forehead, short philtrum, retromicrognathia, large and low set ears, hyperlaxity, overcrowed teeth, dorsal kyphosis, and macropenis. Karyotype showed a deletion 13q21q31. The deletion was de novo and pure. In conclusion this case with sexual precocity and small final stature could be an example of progenesis, rising the question of the presence of a critical region for human evolution within chromosomal region 13q21q31.