Mosaic microdeletion of 17p11.2-p12 and duplication of 17q22-q24 in a girl with Smith-Magenis phenotype and peripheral neuropathy.

We report on a girl with a de novo mosaic derivative chromosome 17 involving a 7.4 Mb deletion of chromosome region 17p11.2 to 17p12 and a duplication of a 12.35 Mb region at 17q22 to 17q24. She was ascertained because of developmental delay, peripheral neuropathy, brachydactyly and minor anomalies. The derivative chromosome was present in approximately 12% of lymphocytes based on FISH studies, and was detected by array comparative genomic hybridization. To our knowledge, this is the third case of mosaicism involving deletion of the 17p11.2 region and the lowest level of mosaicism reported in a patient with Smith-Magenis syndrome (SMS).