Genetic Linkage of the Dentinogenesis Imperfecta Type III Locus to Chromosome 4q

Posted in Articles, Health/Medicine/Genetics, Media Archive, Tri-Racial Isolates, United States on 2011-01-07 02:51Z by Steven

Genetic Linkage of the Dentinogenesis Imperfecta Type III Locus to Chromosome 4q

Journal of Dental Research
Volume 78, Number 6 (June 1999)
pages 1277-1282
DOI: 10.1177/00220345990780061301

M. MacDougall
Department of Pediatric Dentistry
University of Texas Health Science Center, San Antonio

L. G. Jeffords
Department of Pediatric Dentistry,
University of Texas Health Science Center, San Antonio

T. T. Gu
Department of Pediatric Dentistry
University of Texas Health Science Center, San Antonio

C. B. Knight
Department of Pediatric Dentistry
University of Texas Health Science Center, San Antonio

G. Frei
Department of Pediatric Dentistry,
University of Texas Health Science Center, San Antonio

B. E. Reus
Department of Cellular and Structural Biology
University of Texas Health Science Center, San Antonio

B. Otterud
Department of Human Genetics
Eccles Institute of Human Genetics
University of Utah School of Medicine, Salt Lake City

M. Leppert
Department of Human Genetics
Eccles Institute of Human Genetics
University of Utah School of Medicine, Salt Lake City

R. J. Leach
Department of Cellular and Structural Biology
University of Texas Health Science Center, San Antonio

Dentinogenesis imperfecta type III (DGI-III) is an autosomal-dominant disorder of dentin formation which appears in a tri-racial southern Maryland population known as the “Brandywine isolate”. This disease has suggestive evidence of linkage to the long arm of human chromosome 4 (LOD score of 2.0) in a family presenting with both juvenile periodontitis and DGI-III. The purpose of this study was to screen a family presenting with only DGI-III to determine if this locus was indeed on chromosome 4q. Furthermore, we wanted to determine if DGI-III co-localized with dentinogenesis imperfecta type II (DGI-II), which has been localized to 4q21-q23. Therefore, a large kindred from the Brandywine isolate was identified, oral examination performed, and blood samples collected from 21 family members. DNA from this family was genotyped with 6 highly polymorphic markers that span the DGI-II critical region of chromosome 4q. Analysis of the data yielded a maximum two-point LOD score of 4.87 with a marker for the dentin matrix protein 1 (DMP1) locus, a gene contained in the critical region for DGI-II. Our results demonstrated that the DGI-III locus is on human chromosome 4q21 within a 6.6 cM region that overlaps the DGI-II critical region. These results are consistent with the hypothesis that DGI-II is either an allelic variant of DGI-III or the result of mutations in two tightly linked genes.

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