title: Ring D 1  chromosome with remarkable morphological variation in a boy with mental retardation.
mesh_terms: D000293:Adolescent; D002869:Chromosome Aberrations; D002901:Chromosomes, Human, 13-15; D006570:Heterochromatin; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male
chemical_list: D006570:Heterochromatin