ESPE Abstracts

Introduction: A derivative chromosome (der) is a structurally rearranged chromosome generated either by a chromosome rearrangement involving two or more chromosomes or by multiple chromosome aberrations within a single chromosome. Balanced segmental anomalies such as inversion or translocation can lead to derivative chromosomes with partial duplication and deletion during meiosis. Here we present two patients with hypergonadotropic hypogonadism and various accompanying influencesrelated toderivative X chromosome.

Case 1: A 14-year-old girl was hospitalized with hyperglycemic ketosis. Appropriate fluid and insulin therapy was administered. Her body weight and height were at 25 percentile, pubertal examination was Tanner stage 5 and she had mild acanthosis nigricans. HbA1C:16%, Cpeptide:1.18 ng/ml, diabetic autoantibodies were negative. Insulin therapy was discontinued with the initiation of metformin. When evaluated for oligomenorrhea, FSH:49mIU/ml, LH:20mIU/ml, E2:23pg/mL; normal uterus and small right ovary consistent with puberty stage were detected, left ovary could not be visualized inpelvic sonography and MRI. Genetic analysis for ovarian failure and MODYrevealed 46,X, der(X)t(X;X)(q21;p21). Refinement of (der)X with microarraywas planned.

Case 2: A 10.3-year-old girl followed with epilepsy, cognitive retardation and iris coloboma was referred for obesity. She had a seizure at the age of 1, epileptic focus was detected in EEG and antiepileptic treatment was started. Her seizures did not recur afterwards but she continued treatment with valproic acid because of existingepileptic activity in EEG. Her obesity started after infancy and she used to have a high-calorie diet. Her body weight was +3SD, height was +1.67SD, body mass index was +2.6 SD, pubertal examination was Tanner Stage I. FSH:28 mIU/ml, LH:4 mIU/ml, E2:<11 pg/ml were consistent with hypergonadotropic hypogonadism.46,X, der(X)t(X;X)(p11.4;q21) was found inher microarray studied for copy number variation due to neurological findings.

Conclusion: Derivative X chromosomes with preserved X inactivation center (XIST) located at Xq13.2, as in both patients presented, are expected to be prone to inactivation. For this reason, serious clinical problems are not seen despite large segmental imbalances. However, problems such as long stature, ovarian failure, obesity, diabetes, global developmental delay and epilepsy can be seen in female individuals with a short arm duplication of the X chromosome containing PAR1 and a long arm deletion containing PAR2.