Prenatal diagnosis of mosaic tetrasomy 10p associated with megacisterna magna, echogenic focus of left ventricle, umbilical cord cysts and distal arthrogryposis.

We present the first report of mosaic isochromosome 10p associated with multiple congenital anomalies including megacisterna magna, echogenic focus of the left ventricle, umbilical cord cysts, and distal arthrogryposis. The most obvious anomalies found on prenatal ultrasound were enlarged cisterna magna and lower limb flexion contractures which resembled clubfeet. Analyses of GTG-banded chromosomes of 42 cells harvested from 32 independent tissue culture colonies were examined. Thirty-five cells from 27 colonies had 46 chromosomes and appeared to be 46,XX, female karyotype. Seven cells from independent colonies had 47 chromosomes with abnormal karyotypes. The extra chromosome material was identified as isochromosome 10p without involvement of the heterochromatic region of the long arm [47,XX,+ i(10p)]. Mosaic tetrasomy 10p was confirmed using fluorescent in situ hybridization (FISH) of a 10p-specifie probe to metaphase chromosomes of this patient. (C) 2003 Wiley-Liss, Inc.