My cousin just had her baby this morning and he was born with oesophagus defects and NO anus! What causes this? Will he be retarded?

Anal atresia. is often associated with a number of defects of the esophagus. This problem occurs between 4 and 8 weeks of pregnancy likely as a combination of genetic and environmental factors. There are many other possible associated conditions with this. Please review the link below for much more information. http://ghr.nlm.nih.gov/condition/esophageal-atresia-tracheoesophageal-fistula.