Enlarged short arms of a small acrocentric chromosome in relatives of a boy with Down's syndrome.
D000293:Adolescent; D000328:Adult; D000368:Aged; D002869:Chromosome Aberrations / Q000235:genetics*; D025063:Chromosome Disorders; D002904:Chromosomes, Human, 21-22 and Y; D004314:Down Syndrome; D005260:Female; D006801:Humans; D007223:Infant; D007361:Intelligence Tests; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D011569:Psychiatric Status Rating Scales