Abstract
RNA and type I collagen were analyzed from cultured skin fibroblasts of a Beagle puppy with fractures consistent with type III osteogenesis imperfecta (OI). In a nonisotopic RNAse cleavage assay (NIRCA), the proband's RNA had a unique cleavage pattern in the region of COL1A2 encoding the C-propeptide. DNA sequence analyses identified a mutation in which nucleotides 3991-3994 ("CTAG") were replaced with "TGTCATTGG." The first seven bases of the inserted sequence were identical to nucleotides 4002-4008 of the normal canine COL1A2 sequence. The resulting frameshift changed 30 amino acids and introduced a premature stop codon. Reverse-transcription polymerase chain reaction (RT-PCR) with primers flanking the mutation site amplified two complementary DNA (cDNA) fragments for the proband and a single product for the control. Restriction enzyme digestions also were consistent with a heterozygous mutation in the proband. Type I procollagen labeled with [3H]proline was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Increased density of pC-α2(I) suggested comigration with the similarly sized pro-α2(I) derived from the mutant allele. Furthermore, α-chains were overhydroxylated and the ratio of α1(I):α2(I) was 3.2:1, consistent with the presence of α1(I) homotrimers. Analyses of COL1A2 and type I collagen were both consistent with the described heterozygous mutation affecting the pro-α2(I) C-propeptide and confirmed a diagnosis of OI.
Original language | English |
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Pages (from-to) | 1147-1153 |
Number of pages | 7 |
Journal | Journal of Bone and Mineral Research |
Volume | 16 |
Issue number | 6 |
DOIs | |
State | Published - 2001 |
Keywords
- COL1A2
- Canine
- Frameshift
- Osteogenesis imperfecta
- Pro-α2(I)
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Orthopedics and Sports Medicine