Moving towards a syndrome: a review of 20 cases and a new case of non-mosaic tetrasomy 9p with long-term survival

Tetrasomy 9p is a rare syndrome that has now been described in nearly a score of cases. We present a new case of i(9p) that presented to us early in infancy with significant dysmorphological features, including growth retardation, psycho-motor delay, hemifacial microsomia, auditory canal atresia, high-arched palate, bulbous nose, strabismus, epicanthic folds, congenital heart disease, dislocated hips, hypoplastic external genitalia, simian palmar creases, dysplastic nails and small digits. Chromosomal analysis revealed a 47,XX,idic(9)(q12) karyotype on GTG- and C-banding studies on peripheral blood lymphocytes. Fluorescent in situ hybridization (FISH) studies confirmed the origin of the extra chromosome. A review of the literature and a comparative analysis of the several well-documented cases of i(9p) revealed a pattern of recurring features, including ear malformations, skeletal and joint problems (especially dislocations), hypoplasia of nails and digits, palatal abnormalities, hypertelorism, urogenital anomalies and developmental retardation. In the light of this analysis, we feel that tetrasomy 9p will soon be considered a clinically recognizable syndrome.