Maternal serum alpha fetoprotein levels are used for screening all of the following congenital defects, EXCEPT:

Talipes equinovarus is the most common congenital malformation of the foot and may be unilateral or bilateral. It can be diagnosed antenatally by 12 weeks of gestation using ultrasound. In this there is varus of the heel, equines deformity and varus deformity of the forefoot. It can occur as a complication of amniocentesis, when it is done before 13 weeks of gestation. Ref: Oxford Handbook of Genetics By Guy Bradley-Smith, Page 370 ; The Cambridge Encyclopedia of Human Paleopathology By Ahur C. Aufderhei, Page 75 ; Children's Ohopaedics and Fractures By Michael Benson, 3rd Edition, Page 540 ; Textbook of Obstetrics By D.C.Dutta, 6th Edition, Page 107 ; Clinical Genetics in Nursing Practice By Felissa R. Lashley, 3rd Edition, Chapter 12