Hello, My daughter is 10 years old weights 59 pound very leggy always had trouble getting up from the sitting position , running and going up steps has to use both feet instaed of one foot very danty small bone but she is 4feet 5 inches,John Hopkins Hospital check her and said low muscle tone but I feel its more she had small kidneys when she was born or under size they said. gets out of breath when is does run . My youngest son has Down syndrome , could my daughter have some also have a chromzone defeat too , like triple x or some other,, Thank you Bonnie Leuschner