Peripheral retinopathy in offspring of carriers of Norrie disease gene mutations. Possible transplacental effect of abnormal Norrin.
BACKGROUND
The Norrie disease (ND) gene (Xp11.3) (McKusick 310600) consists of one untranslated exon and two exons partially translated as the Norrie disease protein (Norrin). Norrin has sequence homology and computer-predicted tertiary structure of a growth factor containing a cystine knot motif, which affects endothelial cell migration and proliferation. Norrie disease (congenital retinal detachment), X-linked primary retinal dysplasia (congenital retinal fold), and X-linked exudative vitreoretinopathy (congenital macular ectopia) are allelic disorders.


METHODS
Blood was drawn for genetic studies from members of two families to test for ND gene mutations. Sixteen unaffected family members were examined ophthalmologically. If any retinal abnormality were identified, fundus photography and fluorescein angiography was performed.


RESULTS
Family A had ND (R109stp), and family B had X-linked exudative vitreoretinopathy (R121L). The retinas of 11 offspring of carrier females were examined: three of seven carrier females, three of three otherwise healthy females, and one of one otherwise healthy male had peripheral inner retinal vascular abnormalities. The retinas of five offspring of affected males were examined: none of three carrier females and none of two otherwise healthy males had this peripheral retinal finding.


CONCLUSIONS
Peripheral inner retinal vascular abnormalities similar to regressed retinopathy of prematurity were identified in seven offspring of carriers of ND gene mutations in two families. These ophthalmologic findings, especially in four genetically healthy offspring, strongly support the hypothesis that abnormal Norrin may have an adverse transplacental (environmental) effect on normal inner retinal vasculogenesis.
Mintz-Hittner
H A
HA
Department of Ophthalmology and Visual Science, University of Texas Houston Medical School, Houston, USA.
Ferrell
R E
RE
Sims
K B
KB
Fernandez
K M
KM
Gemmell
B S
BS
Satriano
D R
DR
Caster
J
J
Kretzer
F L
FL
D000328:Adult; D000595:Amino Acid Sequence; D001766:Blindness / Q000151:congenital / Q000235:genetics*; D002675:Child, Preschool; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D005451:Fluorescein Angiography; D005654:Fundus Oculi; D005796:Genes; D008040:Genetic Linkage / Q000235:genetics; D006319:Hearing Loss, Sensorineural / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D008297:Male; D008431:Maternal-Fetal Exchange / Q000235:genetics*; D008969:Molecular Sequence Data; D010375:Pedigree; D017354:Point Mutation; D011247:Pregnancy; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012164:Retinal Diseases / Q000235:genetics* / Q000473:pathology; D012171:Retinal Vessels / Q000002:abnormalities / Q000473:pathology; D014960:X Chromosome / Q000235:genetics
D005136:Eye Proteins