Blaschkolinear skin pigmentary variation due to trisomy 7 mosaicism.

Mosaic trisomy 7 is a rare condition that can be seen in individuals with Blaschkolinear skin pigmentary variation, somatic asymmetry, and variable other clinical anomalies. In any patient presenting with Blaschkolinear skin pigmentary variation, varying degrees of asymmetrical growth disturbance, developmental delay, and a normal lymphocytic karyotype, chromosomal mosaicism may be present. To rule out tissue-specific or occult chromosomal mosaicism, it is recommended to culture and karyotype skin fibroblasts, since lymphocyte cell lines may not demonstrate the abnormal cell line. Early diagnosis is of paramount importance, since early physical, occupational, and speech/language therapy can greatly improve the developmental outcome of these patients. We report on a fourth patient with trisomy 7 mosaicism in whom early diagnosis and developmental therapy contributed to an improved developmental outcome when compared with patients in previous reports. Early intervention can greatly benefit patients with this diagnosis, especially in minimizing the aggressive behavior associated with communication difficulties. Our patient has milder manifestations than the previously reported patients with no seizure activity or asymmetry and fewer cells with trisomy 7.