An anonymous single copy chromosome 21 probe, DS21D2, associated with a frequent RFLP.

SOURCE/DESCRIPTION An EcoRI 4.0 kb single copy fragment insert into XgtWES Xb isolated from the chromosome. 21 flow-sorted library of Krumlauf et al (1982). POLYMORPHISM TaqI (T-J-CGA) identifies 2 invariant bands and a simple 2 allele polymorphism with a band at 8.4 and/or 5.8 kb. FREQUENCY St-ndled 10 unrelated individuals. 8.4 kb allele (Al) 0.65 5.8 kb allele (A2) 0.35 CHROMOSOMAL LOCALISATION Unique to chromosome 21 based on Southern blot data to normal human DNA and to that of a mouse-human somatic cell hybrid containing human 21 alone. MENDELIAN INHERITANCE Co-dominant segregation in three informative pedigrees (Utah Pedigrees K-1329, K-1331,and K-1333), 28 individuals. PROBE AVAILABILITY Probe is available for collaborative investigations pending signing of confidentiality agreement. OTHER COMMENTS No problems with RFLP analysis using standard digestion conditions.struction and characterization of genomic libraries from specific human chromosomes. PNAS 79:2971-2975 (1982). ACKNOWLEDGEMENTS We wish to thank Lorraine Cummings and George Mandybur for their expert technical assistance.