| Pituitary abnormality that causes abnormally fast growth in infancy or early childhood. Individuals may present with hyperplasia of the pituitary gland or a benign pituitary adenoma. Rarely both pituitary hyperplasia and an adenoma may be present. The abnormal pituitary gland releases excess amounts of growth hormone and in some cases excess amounts of growth hormone releasing hormone. Additional manifestations of the disorder include coarse facial features, acral enlargement, an increased appetite and acanthosis nigricans. Caused by duplication on the X chromosome, the duplication, often referred to as an Xq26.3 microduplication, occurs on the long (q) arm of the chromosome at a location designated q26.3. The disease follows an X-linked dominant inheritance pattern. In females, the condition results from de novo duplications involving the GPR101 gene. In males, the condition often results from somatic mosaicism. Other affected males inherit the duplication from their affected mother. |
