Electroretinographic findings in three family members with X-linked juvenile retinoschisis associated with a novel Pro192Thr mutation of the XLRS1 gene.
OBJECTIVE
To present ocular findings in three family members with X-linked juvenile retinoschisis (XLRS) associated with a novel Pro192Thr mutation.


METHODS
We examined 21- (Case 1), 17- (Case 2), and 10-year-old (Case 3) male patients who showed wheel-like cystic lesions in the macula and a silver-gray reflex in the peripheral retina. Case 2 was a cousin of Case 1. Case 3 was a brother of Case 2.


METHODS
Scotopic electroretinogram (ERG) (dim and bright flash), oscillatory potentials, photopic ERG, and 30-Hz flicker responses were recorded in each patient. The XLRS1 gene was analyzed in patient blood samples by a direct sequencing method.


RESULTS
A novel missense mutation (Pro192Thr) was identified in the XLRS1 gene in each patient. Variable b/a ratios upon scotopic bright flash stimulation were evident (Case 1: right 1.16, left 1.20; Case 2: right 0.98, left 1.01; Case 3: right 0.81, left 0.83). Only Case 3 showed the typical "negative" waveform. The amplitude of rod b-waves was significantly decreased in all patients.


CONCLUSIONS
Three cases with a novel Pro192Thr mutation showed the phenotypic variation in ERG, especially in b/a ratio, which has been considered an important diagnostic parameter.
Tanimoto
Naoyuki
N
Division of Ophthalmology and Visual Science, Graduate School of Medical and Dental Sciences, Niigata University, Japan.
Usui
Tomoaki
T
Takagi
Mineo
M
Hasegawa
Shigeru
S
Abe
Haruki
H
Sekiya
Keigo
K
Miyagawa
Yasuhiro
Y
Nakazawa
Mitsuru
M
D000293:Adolescent; D000328:Adult; D001483:Base Sequence / Q000235:genetics; D002648:Child; D041321:Chromosomes, Human, X; D004247:DNA / Q000235:genetics; D004596:Electroretinography; D005136:Eye Proteins / Q000235:genetics*; D008040:Genetic Linkage; D006801:Humans; D008297:Male; D020125:Mutation, Missense / Q000502:physiology*; D010375:Pedigree; D010775:Photic Stimulation; D011392:Proline; D012160:Retina / Q000503:physiopathology*; D017948:Retinal Rod Photoreceptor Cells / Q000503:physiopathology; D041441:Retinoschisis / Q000235:genetics* / Q000503:physiopathology*; D013912:Threonine
D005136:Eye Proteins; C108726:RS1 protein, human; D013912:Threonine; D004247:DNA; D011392:Proline