Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028738 (nystagmus)
 7,431 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We isolated and characterized the entire coding sequence of a human gene encoding a protein that interacts with RPGR, a protein that is absent or mutant in many cases of X-linked retinitis pigmentosa. The newly identified gene, called "RPGRIP1" for RPGR-interacting protein (MIM 605446), is located within 14q11, and it encodes a protein predicted to contain 1,259 amino acids. Previously published work showed that both proteins, RPGR and RPGRIP1, are present in the ciliary structure that connects the inner and outer segments of rod and cone photoreceptors. We surveyed 57 unrelated patients who had Leber congenital amaurosis for mutations in RPGRIP1 and found recessive mutations involving both RPGRIP1 alleles in 3 (6%) patients. The mutations all create premature termination codons and are likely to be null alleles. 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.
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PMID:Null RPGRIP1 alleles in patients with Leber congenital amaurosis. 1128 94

Albinism ocular type 1 (OA1) is an X-linked type of albinism that mainly effects pigment production in the eye, resulting in hypopigmentation of the retina, nystagmus, strabismus, foveal hypoplasia, abnormal crossing of the optic fibers, and reduced visual acuity. The OA1 gene is located on chromosome Xp22.32 and the coding sequence is divided into nine exons. The protein is an integral transmembrane protein that has weak similarities to G protein-coupled receptors. A total of 25 missense, two nonsense, nine frameshift, and five splicing mutations have been reported in the OA1 gene associated with OA1. There are also several deletions of some or all exons of the OA1 gene with deletions of exon 2 resulting from unequal crossing-over, due to flanking Alu repeats. Mutation and polymorphism data on this gene is available from the International Albinism Center - Albinism Database web site (http://www.cbc.umn.edu/tad).
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PMID:New insights into ocular albinism type 1 (OA1): Mutations and polymorphisms of the OA1 gene. 1179 67

X-linked CSNB patients may exhibit myopia, nystagmus, strabismus and ERG abnormalities of the Schubert-Bornschein type. We recently identified the retina-specific L-type calcium channel alpha1 subunit gene CACNA1F localised to the Xp11.23 region, which is mutated in families showing the incomplete type (CSNB2). Here, we report comprehensive mutation analyses in the 48 CACNA1F exons in 36 families, most of them from Germany. All families were initially diagnosed as having the incomplete type of CSNB, except for two which have been designated as Aland Island eye disease (AIED)-like. Out of 33 families, a total of 30 different mutations were identified, of which 24 appear to be unique for the German population. The mutations, 20 of which are published here for the first time, were found to be equally distributed over the entire gene sequence. No mutation could be found in a classic AIED family previously shown to map to the CSNB2 interval. Cacna1f expression in photoreceptor-negative mice strains indicate that the gene is expressed in the outer nuclear, the inner nuclear, and the ganglion cell layer. Such a distribution points to the central role of calcium regulation in the interaction of retinal cells that mediate signal transmission.
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PMID:Thirty distinct CACNA1F mutations in 33 families with incomplete type of XLCSNB and Cacna1f expression profiling in mouse retina. 1211 38

Albinism is a group of inherited conditions in which affected individuals have less than normal pigment in the eyes, skin, and hair compared to others of the same race and ethnic background. The prevalence of all types of albinism in the United States is estimated at 1 in 20,000, based on poor epidemiological data. X-linked Nettleship-Falls ocular albinism (XLOA, OA1) affects approximately 1/150,000 males in the population. XLOA effects reduce visual acuity and nystagmus, result in a mild skin and hair phenotype, and occur mostly in XY males. Female carriers of XLOA have normal visual acuity, but often show iris punctate transillumination and a classic pattern of mosaic retinal pigmentation, coarse and grainy in the macula and becoming increasingly reticular into the periphery of the retinal pigment epithelium. Studies of OA1 have shown linkage of a single gene to markers at Xp22.3-p22.2. About 48% of the reported mutations in the OA1 gene are intragenic deletions and about 43% are point mutations. We present a hierarchical strategy for mutation screening for diagnostic testing for OA1 that comprises two tiers: first, multiplex PCR to detect intragenic deletions in the OA1 gene with denaturing high-performance liquid chromatography (dHPLC), and, second, heteroduplex analysis with dHPLC to scan for mutations, with subsequent sequencing of variants to confirm putative mutations in the OA1 gene. Prenatal diagnosis can be provided for families when the mutation has been firmly identified. We have validated this procedure with positive controls that were identified in patients by Southern blot, single-stranded conformation polymorphism (SSCP), and sequencing. In this hierarchical strategy, these procedures have an analytical sensitivity of > 99%.
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PMID:Diagnostic DNA testing for X-linked ocular albinism (OA1) with a hierarchical mutation screening protocol. 1218 81

X-linked congenital stationary night blindness (CSNBX) is a genetically and phenotypically heterogeneous non-progressive disorder, characterised by impaired night vision but grossly normal retinal appearance. Other more variable features include reduction in visual acuity, myopia, nystagmus and strabismus. Genetic mapping studies by other groups, and our own studies of British patients, identified key recombination events indicating the presence of at least 2 disease genes on Xp11. Two causative genes (CACNA1F and NYX) for CSNBX have now been identified through positional cloning strategies. In this report, we present the results of comprehensive mutation screening in 14 CSNBX families, three with mutations in the CACNA1F gene and 10 with mutations in the NYX gene. In one family we failed to identify the mutation after testing RP2, RPGR, NYX and CACNA1F. NYX gene mutations are a more frequent cause of CSNBX, although there is evidence for founder mutations. Our report of patient population mutation screening for both CSNBX genes, and our exclusion of RP2 and RGPR, indicates that mutations in CACNA1F and NYX are likely to account for all CSNBX.
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PMID:Mutations in the CACNA1F and NYX genes in British CSNBX families. 1255 65

Ocular albinism type 1 (OA1) is an X-linked disorder, mainly characterized by a severe reduction in visual acuity, foveal hypoplasia, nystagmus, hypopigmentation of the retina, the presence of macromelanosomes in the skin and eyes, and the misrouting of optic pathways, resulting in the loss of stereoscopic vision. We screened the OA1 gene for mutations in three unrelated Canadian and French families and in two isolated patients with OA1. We found three different missense mutations and two different nonsense mutations, three of which were novel. To date, 41 mutations (including missense mutations, insertions, and deletions) have been reported in the OA1 gene. Mutation and polymorphism data for this gene are available from the international albinism center albinism database website: http://www.cbc.umn.edu/tad/oa1map.htm.
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PMID:Mutational analysis of the OA1 gene in ocular albinism. 1286 35

Pelizaeus-Merzbacher disease and X-linked spastic paraplegia type 2 are two sides of the same coin. Both arise from mutations in the gene encoding myelin proteolipid protein. The disease spectrum for Pelizaeus-Merzbacher disease and spastic paraplegia type 2 is extraordinarily broad, ranging from a spastic gait in the pure form of spastic paraplegia type 2 to a severely disabling form of Pelizaeus-Merzbacher disease featuring hypotonia, respiratory distress, stridor, nystagmus, and profound myelin loss. The diverse disease spectrum is mirrored by the underlying pathogenesis, in which a blockade at any stage of myelin proteolipid protein synthesis and assembly into myelin spawns a unique phenotype. The continuing definition of pathogenetic mechanisms operative in Pelizaeus-Merzbacher disease and spastic paraplegia type 2, together with advances in neural cell transplant therapy, augurs well for future treatment of the severe forms of Pelizaeus-Merzbacher disease.
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PMID:Pelizaeus-Merzbacher disease and spastic paraplegia type 2: two faces of myelin loss from mutations in the same gene. 1457 40

We investigated the nystagmus of a 12-year-old boy with suspected X-linked congenital nystagmus (CN) and exophoria to determine the underlying mechanisms and component signals in the 'dual-velocity' and other slow phases of his Asymmetric (a)Periodic Alternating Nystagmus (APAN). Fast Fourier transforms (FFT) were performed on the waveforms and residual data after subtracting a sawtooth waveform whose amplitude and frequency matched those of the jerk nystagmus. The FFT analyses identified two frequency components (jerk--4 Hz and pendular--4 and 8 Hz, variable) that varied differently in intensity and frequency/phase over the time-course of the APAN. We synthesized each of the patient's slow phases using summation of sawtooth and sinusoidal waveforms. The resulting waveforms included jerk (with different slow-phase appearances), dual jerk, and pendular. We demonstrated that the pendular nystagmus seen during the neutral phase of APAN and the appearance of either decelerating (mimicking latent nystagmus), dual-velocity, or dual-jerk slow phases can be explained and produced by the summation of linear and pendular components of variable amplitudes and frequencies/phases. Thus, one mechanism may be responsible for all the variation seen in this patient's slow phases, rather than the less parsimonious hypothesis of a switched-tonic-imbalance mechanism that we had originally suggested to simulate the dual-velocity waveform.
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PMID:Time-varying, slow-phase component interaction in congenital nystagmus. 1463 69

The hypomyelinating leukodystrophies X-linked Pelizaeus-Merzbacher disease (PMD) and Pelizaeus-Merzbacher-like disease (PMLD) are characterized by nystagmus, progressive spasticity, and ataxia. In a consanguineous family with PMLD, we performed a genomewide linkage scan using the GeneChip Mapping EA 10K Array (Affymetrix) and detected a single gene locus on chromosome 1q41-q42. This region harbors the GJA12 gene, which encodes gap junction protein alpha 12 (or connexin 46.6). Gap junction proteins assemble into intercellular channels through which signaling ions and small molecules are exchanged. GJA12 is highly expressed in oligodendrocytes, and, therefore, it serves as an excellent candidate for hypomyelination in PMLD. In three of six families with PMLD, we detected five different GJA12 mutations, including missense, nonsense, and frameshift mutations. We thereby confirm previous assumptions that PMLD is genetically heterogeneous. Although the murine Gja12 ortholog is not expressed in sciatic nerve, we did detect GJA12 transcripts in human sciatic and sural nerve tissue by reverse-transcriptase polymerase chain reaction. These results are in accordance with the electrophysiological finding of reduced motor and sensory nerve conduction velocities in patients with PMLD, which argues for a demyelinating neuropathy. In this study, we demonstrate that GJA12 plays a key role in central myelination and is involved in peripheral myelination in humans.
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PMID:Mutations in the gene encoding gap junction protein alpha 12 (connexin 46.6) cause Pelizaeus-Merzbacher-like disease. 1519 6

Pelizaeus-Merzbacher disease is a rare X-linked disease characterized by defective central nervous system myelination owing to a mutation in the proteolipid protein 1 gene. Few studies report detailed clinical findings in children with genetic confirmation of mutations in the proteolipid protein 1 gene. We reviewed the records of 10 boys with Pelizaeus-Merzbacher disease and one symptomatic carrier girl. Their median age was 2 1/2 years (range 10 months to 20 years). Nine had proteolipid protein 1 gene duplications, one had a point mutation, and one had a single codon deletion. The families of eight patients reported perinatal complications, including maternal hypertension (three patients) and meconium aspiration (three patients). All of the patients were social and interactive, but all had difficulty with expressive speech. All patients presented with nystagmus and had hypotonia that progressed to spasticity, affecting the legs more than the arms; ataxia also contributed to motor impairment. Additional problems reported regarded feeding (eight patients) and sleep (three patients). Further work is needed to clarify the variations in disease course and the relationship of genotype to phenotype.
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PMID:Clinical findings in Pelizaeus-Merzbacher disease. 1522 5


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