Gonadal dysgenesis, intra-X chromosome insertion, and possible position effect in an otherwise normal female.

A 16-year-old female was referred for cytogenetic evaluation because of primary amenorrhea. Growth, mental development, and physical examination, including secondary sexual characteristics, were normal. Cytogenetic analysis revealed one X chromosome to be consistently more metacentric than the other. Measurements indicted no significant differences between the two X's, but in the abnormal X, the increase in length of the short arm matched the decrease in length of the long arm. Banding studies suggest that region q22 through q24 of the abnormal X is inserted into region p11 of the same chromosome. Endocrine studies were indicative of gonadal dysgenesis. Since no loss of X chromosome material is involved, this patient's gonadal dysgenesis is most likely related to position effect.