To the Editor:—
The karyotype of a 21-year-old female college student with short forearms and a maternal history of two generations (Dr. Mario Montes, personal communication) revealed a chromosome abnormality not heretofore described: A D-like chromosome with satellited prominent short arms was seen in 33 of 35 metaphases (Figure).The variable density of the acetoorcein stain resembled that expected from superimposition of a small acrocentric chromosome with satellites or of satellited isochromosome fragments on the heterochromatic short arms of a D chromosome, following an incomplete break at the centromere. The unmatched chromosome was unlabeled after three hours' exposure to tritiated thymidine, as is the asynchronous early-labeling D3 (15) homologue.1Family studies were not possible; it is uncertain, then, whether the unmatched chromosome is fortuitous or is associated with the history of familial short arms.
Kelly S. Short Forearms and A Unique D Chromosome. JAMA. 1969;209(3):418. doi:10.1001/jama.1969.03160160054022