A case of extra small acrocentric bisatellited chromosome in a non mongoloid child.

A mentally retarded child with an extra small bisatellited acrocentric chromosome is described. The patient exhibited rather unspecific clinical signs such as strabismus, marked facial asymmetry, broad and prominent nasal bridge, hypertelorism, Brushfield's spots, malformed ears with atresia of the external auditory canal on the right side. Giemsa banding (R and G methods) did not allow a clear cytogenetic identification of the extra-chromosome. A tentative interpretation of the cytogenetic aberration as a trisomy of the proximal part of the long arm of chromosome 13 is discussed.