Pure partial trisomy 4q syndrome in a child with der(9)ins(9;4)(q34.3;q26q35.2)mat

Pure partial trisomy 4q syndrome in a child with der(9)ins(9;4)(q34.3;q26q35.2)mat: Partial trisomy 4q is a rare chromosomal abnormality and mostly results from unbalanced inheritance of balanced parental chromosomal translocations. Here, we present a 5-year-old boy with partial trisomy 4q who exhibited distinctive features of 'pure' partial trisomy 4q syndrome including moderate mental and growth retardation, microcephaly, peculiar face appearance, tooth anomaly, cleft palate, language handicap, preaxial polydactyly, and urogenital anomaly. Karyotype analysis of the child revealed der(9)ins(9;4)(q34.3;q26q35.2) inherited from mother carrying ins(9;4)(q34.3;q26q35.2) resulting in trisomy of the 4q26qter segment. Whole chromosome painting, locus specific, and subtelomeric FISH analysis in mother proved that q26qter of the chromosome 4 segment was directly inserted into the telomeric sequence in chromosome 9, and depending on nature of the rearrangement in mother, karyotype of the child was determined to be pure partial 4q trisomy. This is the first report of this kind of rearrangement causing pure partial trisomy 4q with accompanying white matter change demonstrated by MRI and bilateral preaxial polydactyly of both hands.