Abstract
Noonan's syndrome is characterized by clinical features which resemble Turner's syndrome and by a normal karyotype.
A 20-yr-old man was referred to us for short stature and thirst. His birth weight was 2500 g and his growth had been retarded. At the age of 12, he was diagnosed as having depression and was treated with antidepressants. At the age of 20, thirst, polydipsia, polyuria and emaciation developed. There was no family history of short stature and diabetes mellitus. Physical examination revealed short stature (148.5cm, 41.3kg), hypertelorism, epicantus, microphthalmus, low set hairline and shield chest. Heart murmur was not heard. Atrophy of the seminal vesicles and prostate was noted with a short penis and small testes. The full scale intelligence quotient (I.Q) was 48.
The karyotype was 46-XY. The human leukocyte antigen (HLA) type was A9, 10, BW40, 51. Dermatoglyphicfindings revealed a bridge type of simian-line and a high axial triradius, and the total fingertip ridge count exceeded 190. Thyroidal and adrenal functions were normal. The plasma testosterone levels before and after human chorionic gonadotropin administration were normal. The basal and stimulated levels of plasma follicle stimulating hormone (FSH) during the luteinizing hormone-releasing hormone (LHRH) test were high. A 100g-glucose tolerance test revealed a diabetic pattern of blood glucose and a low response of immunoreactive insulin (IRI). Growth hormone showed an exaggerated response by the arginine infusion test.
The association of Noonan's syndrome with diabetes mellitus is rare in the literature, although the reason for this is not known.
Mental retardation is often recognized in Noonan's syndrome, while depression, epilepsy and schizophrenia are occasionally found in the syndrome. It is suspected that these psychoses may represent one of the component features of the syndrome.
