Cryptic 6q subtelomeric deletion associated with a paracentric inversion in a mildly retarded child

We report on a girl with minor anomalies and developmental delay carrying an apparently balanced paracentric inversion of chromosome 6q (q22qter). Fluorescent in situ hybridization analysis demonstrated a deletion of the subtelomeric region of 6q. This illustrates the use of specific subtelomeric fluorescent in situ hybridization probes to detect cryptic deletions as an important cause of mental retardation in seemingly balanced chromosome rearrangements.