Partial tetrasomy 9 in a liveborn infant

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Abstract
An unusual rearrangement of chromosome 9 was identified in a male infant with multiple congenital malformations. The rearrangement appeared as a fusion of 2 number 9 chromosomes with similar long-arm breakpoints. Since the infant also possessed 2 normal 9''s, the presence of the additional chromosome resulted in partial tetrasomy: 47,XY, + tdic(9;9)(q22;q22). Clinical and autopsy examinations revealed many features reminiscent of trisomy 13. The tdic was functionally monocentric, although some evidence of activity at the 2nd centromere was observed. Both parents had normal karyotypes, and C[constituitive heterochromatin]-banding demonstrated that at least 1 of the 9h regions on the tdic was likely to be of maternal origin.