Bilateral synergistic convergence associated with homozygous ROB03 mutation (p.Pro771Leu).
OBJECTIVE
To document the phenotype and determine the genotype of a child with synergistic convergence.


METHODS
Interventional case report.


METHODS
Patient and nuclear family (7 members total).


METHODS
Ophthalmologic, neurologic, and radiologic examination of the proband; venous blood sampling for candidate gene testing of the proband; venous blood sampling for confirmatory testing in other family members.


METHODS
Clinical and radiologic observations in proband and candidate gene results.


RESULTS
The proband, a 9-year-old girl, substituted convergence for horizontal gaze (synergistic convergence) since birth. She also had conjugate pendular nystagmus, asynchronous blinking, and high myopia. No family member had ophthalmologic or medical symptoms. Neuroradiologic imaging revealed hindbrain dysplasia and modest scoliosis. Sequencing of ROB03, the gene associated with horizontal gaze palsy and progressive scoliosis, revealed a novel missense mutation (p.Pro771Leu) that altered an evolutionarily conserved amino acid. Screening the family for this mutation confirmed that both parents were carriers and identified 2 sisters as carriers and 2 brothers as noncarriers.


CONCLUSIONS
This is the second reported patient with synergistic convergence and the first associated with a documented pathologic genotype. Unlike the previously reported case (which occurred in the setting of the cranial dysinnervation disorder congenital fibrosis of the extraocular muscles), our patient presumably has a supranuclear cause.


BACKGROUND
The author(s) have no proprietary or commercial interest in any materials discussed in this article.
Khan
Arif O
AO
Division of Pediatric Ophthalmology, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia. arif.khan@mssm.edu
Oystreck
Darren T
DT
Al-Tassan
Nada
N
Al-Sharif
Latifa
L
Bosley
Thomas M
TM
D002648:Child; D003241:Consanguinity; D003290:Convergence, Ocular / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D007839:Functional Laterality; D005838:Genotype; D006801:Humans; D008279:Magnetic Resonance Imaging; D020125:Mutation, Missense; D009419:Nerve Tissue Proteins / Q000235:genetics; D015835:Ocular Motility Disorders / Q000235:genetics*; D010641:Phenotype; D020033:Protein Isoforms / Q000235:genetics; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic / Q000235:genetics*; D012249:Rhombencephalon / Q000002:abnormalities; D012600:Scoliosis / Q000175:diagnosis / Q000235:genetics; D000097905:Roundabout Proteins
D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C499630:ROBO3 protein, human; D000097905:Roundabout Proteins