Chromosome 7 aberrations in a young girl with myelodysplasia and hepatoblastoma: an unusual association.

We report a 30-month-old female with intrauterine growth retardation, postnatal failure to thrive, pancytopoenia and myelodysplasia with monosomy 7 in the marrow. The child succumbed to overwhelming sepsis, following a bone marrow transplant to facilitate chemotherapy for metastatic hepatoblastoma--a tumour that has not been previously reported in myelodysplasia syndromes. Cytogenetic, molecular and microarray analysis of peripheral blood, skin fibroblasts and bone marrow revealed unusual results, suggestive of somatic chromosome instability. A normal peripheral blood karyotype was documented in infancy. Monosomy 7 was found in the bone marrow. Molecular (microsatellite marker) results for a later peripheral blood specimen were suggestive of partial maternal isodisomy 7q, and this was supported by microarray data on single-nucleotide polymorphisms. Microarray data on gene copy number, collected for the same blood specimen, indicated cryptic mosaicism for the monosomy 7 cell line, with the monosomic line lacking the paternal copy. In fibroblasts, cytogenetic data showed mosaic partial trisomy for distal 7p.