Abstract
Purpose: :
The Raz mouse is a radiation–induced mutant resulting from inversion of the centromeric segment of chromosome 5. Raz is a semi–dominant trait where the unique limb phenotype has been previously described. However, the ocular phenotype of the Raz mouse has never been evaluated. The goal of this study is to perform clinical, radiological and histopathological evaluations of the Raz ocular phenotype.
Methods: :
For clinical examination mice were dilated with 1% atropine and examined with a slit lamp. Skull radiographs were performed on mice following anesthesia with ketamine 75 mg/kg and medetomidine 1 mg/kg IP. For histopathology eyes were collected from 3 weeks old mice, serially sectioned with–in the orbit and stained with H&E, trichrome, and alcian blue PAS.
Results: :
Some Raz mice never open their eyes or have only one open eye. Radiological evaluation did not identify any skull or optic cavity abnormalities. The histopathological findings showed hyperkeratosis of the eyelid margin, distichiasis, vascularized and disorganized corneal stroma, broad anterior synechiae, abnormal development of the lens capsule, anterior and nuclear cataracts. Clinical evaluation was consistent with histopathological findings.
Conclusions: :
The Raz mouse shows severe ophthalmological defects consistent with features of anterior segment dysgenesis. The inverted region on chromosome 5 responsible for the Raz phenotype shows synteny with human chromosomes 7q and 4p. The ophthalmological features of the Raz mouse resemble ocular manifestations in some Wolf–Hirschhorn syndrome patients, a disorder caused by sub–telomeric deletions of human chromosome 4p.
Keywords: development • transgenics/knock-outs • mutations