An ultra-rare case of 47,XXY/48,XXXY/49,XXXXY mosaic Klinefelter syndrome associated with diabetic ketosis and foot ulcer

Klinefelter syndrome (KS) is the most common chromosome aneuploidy and a common cause of infertility in males. KS patients have at least one extra X chromosome, and about 80% of patients have the karyotype 47,XXY. Twenty percent of KS patients have higher-grade aneuploidies (48,XXXY, 48,XXYY, 49,XXXXY) and exert some clinical manifestation different from those with 47,XXY. Here we report the case of a young man who initially presented with diabetic ketosis and foot ulcer and was later diagnosed as having an extremely rare mosaic variant of KS (47,XXY/48,XXXY/49,XXXXY). Clinical and laboratory features are summarized. The patient developed a severe foot ulcer with an 18-month history of diabetes. Learning disability was noted since early childhood. The patient had typical manifestations of KS, including increased height, sparse beard and body hair, and small penis. He also had some characteristic features of patients with additional sex chromosomes, including epicanthal folds, narrow palpebral fissures, prominent elbows, and undescended testicles. Severe myopia and myopic macular degeneration was also found. Lab tests revealed low testosterone and elevated FSH but normal LH levels. Chromosome analysis on lymphocytes revealed an aberration of 47,XXY/48,XXXY/49,XXXXY. This case provides information on KS patients with the extremely rare karyotype 47,XXY/48,XXXY/49,XXXXY, and also emphasizes the importance of considering KS in the differential diagnosis of a sterile male with diabetes.