However, it is easily misdiagnosed as congenital idiopathic nystagmus in some Chinese patients with OA1 caused by the G-protein coupled receptor 143 (GPR143) gene mutations.
This study was undertaken to analyse the OA1 gene (GPR143) and its involvement in a Spanish family presenting with nystagmus, a common symptom of X-linked ocular albinism (XLOA).
These results suggest that this novel mutation is associated with the congenital nystagmus observed in this Chinese family and further support that GPR143 mutations are the underlying pathogenesis of the molecular mechanism for congenital nystagmus.
GPR143 mainly affects pigment production in the eye, resulting in optic changes associated with albinism, including hypopigmentation of the retina, nystagmus, strabismus, foveal hypoplasia, abnormal crossing of the optic fibers, and reduced visual acuity.
Variants in RARS1 impair ArgRS activity and do not only lead to a classic hypomyelination presentation with nystagmus and spasticity, but to a wide spectrum, ranging from severe, early-onset epileptic encephalopathy with brain atrophy to mild disease with relatively preserved myelination.
Patients with RPGRIP1 mutations have a degeneration of both rod and cone photoreceptors, and, early in life, they experience a severe loss of central acuity, which leads to nystagmus.
Patients with RPGRIP1 mutations have a degeneration of both rod and cone photoreceptors, and, early in life, they experience a severe loss of central acuity, which leads to nystagmus.
SCA 6 was characterized by frequent occurrence of nystagmus and abnormal pursuit and rarity of slow saccades and ophthalmoparesis and SCA 2 by the frequent occurrence of slow saccades and infrequent nystagmus and dysmetric saccades.
CACNA1A loss-of-function mutations classically present as episodic ataxia type 2 (EA2), with brief episodes of ataxia and nystagmus, or with progressive spinocerebellar ataxia (SCA6).
Beside the growing number of descriptions of novel CACNA1A mutations with episodic ataxia type 2 phenotype; there are only rare reports on interictal oculomotor signs other than nystagmus.
Although clinical features associated with the T666MCACNA1A mutation are highly variable, downbeat positioning nystagmus may be an important clinical feature of this disease.
In over 50% of cases the causative gene is CACNA1A (FHM1), which in some cases produces a phenotype with cerebellar signs, including ataxia and nystagmus.
For the efficient screening of SCA6, we would propose testing CAG repeat expansion in CACNL1A4, in patients with one of two markers: (1) horizontal or oblique gaze nystagmus without other eye movement disorders, (2) pure cerebellar atrophy, even if occurrence is sporadic.