title: Origin and clinical significance of twinning.
mesh_terms: D000015:Abnormalities, Multiple; D001164:Arteriovenous Fistula / Q000151:congenital; D001789:Blood Group Antigens; D004200:Diseases in Twins; D005260:Female; D006330:Heart Defects, Congenital; D006801:Humans; D008297:Male; D009030:Mosaicism; D010920:Placenta; D011247:Pregnancy; D012737:Sex Factors; D014427:Twins; D014428:Twins, Conjoined
chemical_list: D001789:Blood Group Antigens