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August 1971

47,XXY/48,XXXY/49,XXXXY Mosaicism in a 4-Year-Old Child

Author Affiliations

New York
From the Department of Pediatrics, Division of Medical Genetics, Mt Sinai School of Medicine of the City University of New York. Dr. Hirschhorn is a Career Scientist of the Health Research Council of the City of New York (1-513).

Am J Dis Child. 1971;122(2):160-162. doi:10.1001/archpedi.1971.02110020094014

A 4-year-old child with a small penis and small firm testes was found to have XXY/XXXY/XXXXY mosaicism. His growth and development were normal except for delayed speech. Intelligence quotient at 4 years of age was normal. Since Klinefelter's syndrome is usually not diagnosed before puberty, the finding of a small penis and small firm testes in an otherwise normal prepubescent boy should alert the physician to the possibility of this diagnosis.