81000112

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Mosaic Tetrasomy 9p Case with the Phenotype Mimicking Klinefelter Syndrome and Hyporesponse of Gonadotropin-Stimulated Testosterone Production

English (英語)

The Kobe journal of the medical sciences

53(4)

143-150

Kobe University School of Medicine

2007-08

2008-02-20

Tetrasomy 9p is a rare clinical syndrome and about 30% of known cases exhibitchromosome mosaicism. The cases with tetrasomy 9p mosaicism have been reportedto show the various phenotypes. On the other hand, Klinefelter syndrome is wellrecognized chromosomal abnormality caused by an additional X chromosome in males(47,XXY), and the characteristic clinical findings include tall stature, immaturity ofexternal genitalia, testicular dysfunction. Here, we report a 10-year-old male withtetrasomy of 9p mosaicism, whose phenotypic feature is mimicking Klinefeltersyndrome. He was referred to our hospital for inconspicuous penis. He showed tallheight (+2.5 SD). Endocrinological examination revealed the poor testosteroneresponse to human chorionic gonadotropin administration, which indicated thetesticular hypofunction, whereas MRI revealed concealed penis as a cause ofinconspicuous penis. Because of the phenotype mimicking Klinefelter syndrome,karyotype of his blood lymphocytes was analyzed, and an additional markerchromosome was detected in 6% of the investigated metaphases. Fluorescence in situhybridization analysis revealed that the marker chromosome was an isochromosome 9p,which resulted in tetrasomy 9p. Chromosome analysis of buccal smear also showedmosaicism for two karyotypes: 5% of cells had the isochromosome of 9p, and the othercells showed normal. This case is the second case with tetrasomy 9p mosaicismmimicking Klinefelter syndrome phenotype in the world. Our case, together withpreviously reported cases with the same association, indicates the possibility oftesticular hypofunction and urogenital anomalies induced by overexpression of somegenes on chromosome 9p.

concealed penis

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