Is It Normal To Have 4 Vertebrae Instead Of 5 And An Extra Rib?

We just went to a childrens orothopaedic clinic and was told my 15 year old daughter has 4 vertebrae instead of 5 and an extra rib. Was trying to find out if it is common or not. They recommended seeing a P.T 2x week for 8 weeks to build her "core" because she was complaining of back pain. Is this standard?