title: A contracted DNA repeat in LHX3 intron 5 is associated with aberrant splicing and pituitary dwarfism in German shepherd dogs.
abstract: Dwarfism in German shepherd dogs is due to combined pituitary hormone deficiency of unknown genetic cause. We localized the recessively inherited defect by a genome wide approach to a region on chromosome 9 with a lod score of 9.8. The region contains LHX3, which codes for a transcription factor essential for pituitary development. Dwarfs have a deletion of one of six 7 bp repeats in intron 5 of LHX3, reducing the intron size to 68 bp. One dwarf was compound heterozygous for the deletion and an insertion of an asparagine residue in the DNA-binding homeodomain of LHX3, suggesting involvement of the gene in the disorder. An exon trapping assay indicated that the shortened intron is not spliced efficiently, probably because it is too small. We applied bisulfite conversion of cytosine to uracil in RNA followed by RT-PCR to analyze the splicing products. The aberrantly spliced RNA molecules resulted from either skipping of exon 5 or retention of intron 5. The same splicing defects were observed in cDNA derived from the pituitary of dwarfs. A survey of similarly mutated introns suggests that there is a minimal distance requirement between the splice donor and branch site of 50 nucleotides. In conclusion, a contraction of a DNA repeat in intron 5 of canine LHX3 leads to deficient splicing and is associated with pituitary dwarfism.
authors: Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
authors: Annemarie M W Y
authors: AM
authors: Voorbij
authors: Frank G
authors: FG
authors: van Steenbeek
authors: Manon
authors: M
authors: Vos-Loohuis
authors: Ellen E C P
authors: EE
authors: Martens
authors: Jeanette M
authors: JM
authors: Hanson-Nilsson
authors: Bernard A
authors: BA
authors: van Oost
authors: Hans S
authors: HS
authors: Kooistra
authors: Peter A
authors: PA
authors: Leegwater
mesh_terms: D000818:Animals; D001483:Base Sequence; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000235:genetics; D004283:Dog Diseases / Q000235:genetics*; D004285:Dogs / Q000235:genetics*; D004393:Dwarfism, Pituitary / Q000235:genetics / Q000662:veterinary*; D005091:Exons / Q000235:genetics; D020022:Genetic Predisposition to Disease; D005858:Germany; D007438:Introns / Q000235:genetics*; D060850:LIM-Homeodomain Proteins; D008297:Male; D008969:Molecular Sequence Data; D012326:RNA Splicing / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*; D017384:Sequence Deletion / Q000235:genetics; D014157:Transcription Factors
chemical_list: D018076:DNA, Complementary; D060850:LIM-Homeodomain Proteins; C094898:Lhx3 protein; D014157:Transcription Factors