CHROMOSOME 19Q CONE-ROD RETINAL DYSTROPHY - OCULAR PHENOTYPE

Objective: To describe the phenotype in a family with dominantly inher ited cone-rod dystrophy with chromosome assignment to a 19q locus, and to correlate this with current classifications of this retinal dystro phy. Design: A detailed clinical examination including Goldmann perime try was undertaken in all family members. Six members under the age of 30 years underwent dark-adapted electroretinography, color contrast-s ensitivity measurement, dark-adapted static perimetry, and dark adapto metry. Patients: The study included 34 affected and 22 unaffected pati ents in four generations of a pedigree that manifested autosomal domin ant cone-rod retinal dystrophy linked to a chromosome 19q locus by gen etic linkage analysis. Results: Loss of visual acuity occurred in the first decade of life, onset of night blindness occurred after 20 years of age, and little visual function remained after the age of 50 years . Central and, later, peripheral retinal fundus changes were associate d with central scotoma, pseudoaltitudinal field defects, and finally g lobal loss of function. Psychophysical and electrophysiologic testing before the age of 26 years showed more marked loss of cone than rod fu nction. Conclusions: The phenotype associated with this mutation does not fit well into previous subtypes of cone-rod dystrophy. Further stu dies will be needed to correlate specific genetic mutations in this gr oup of conditions with the various clinical phenotypes.