A case of Klinefelter syndrome, mosaicism (46,XY/47,XXY), associated with anorexia nervosa.

We report the case of a 12.4-yr-old boy who presented Klinefelter syndrome (KS) mosaicism (46,XY/47,XXY), associated with mental retardation and anorexia nervosa (AN). KS was undiagnosed before hospitalization in a psychiatric unit. The patient was referred to a child psychiatric unit for restrictive eating. The medical history showed long standing feeding difficulties and failure to thrive. The patient was pre-pubertal and other clinical characteristics were: microcephaly, short stature and dysmorphic traits. Cytogenetic analysis revealed a mosaicism, 46,XY[11] and 47,XXY[19] karyotype. The psychiatric assessment demonstrated the presence of AN and low mood. No specific pathophysiological links between the alterations of KS and the development of AN should be hypothesized on the basis of this case report. In pre-pubertal boys with mental disorders, the possibility of KS should be considered, independently of the presence of eating disorders. Nevertheless, the case shows that KS can be first detected during an assessment for eating disorders. Few cases of the association of KS with AN have been previously reported in literature. This is the first description of KS, mosaicism (46,XY/47,XXY), associated with AN and mental retardation. This case report illustrates the need, for clinicians who work with eating disorders, to investigate the possible association between AN and KS, a rare but intriguing one.