The etiology of congenital generalized lipodystrophy (CGL) is unknown, but one of the clinical features is an accelerated rate of growth. In order to determine whether this abnormality is related to an abnormality of the GH or the IGF-I gene, we studied the DNA of lymphocytes of a girl with CGL. The IGF-I gene autoradiographic patterns of this patient were found not to differ from those of normal subjects, but after BamHI digestion, this patient's GH gene cluster had an aberrant 5.7 kb fragment in addition to the constant 8.3, 6.7, 5.3, 3.8, 2.9 kg fragments. The new 5.7 kb fragment was not detected in any of 60 unrelated Japanese individuals. In conclusion, the CGL patient carries an abnormal GH gene cluster, but further studies are needed to clarify whether this abnormal fragment is specific to CGL or just a rare polymorphic fragment.