1
|
Abstract
PURPOSE OF REVIEW To describe the entity of Lyonization in ocular eye diseases, along with its clinical and counseling implications. RECENT FINDINGS Several X-linked ocular diseases such as choroideremia, X-linked retinitis pigmentosa, and X-linked ocular albinism may have signs of Lyonization on ocular examination and diagnostic testing. These findings may aid in the proper diagnosis of ocular disease in both female carriers and their affected male relatives. SUMMARY Manifestations of Lyonization in the eye may help in the diagnosis of X-linked ocular diseases which may lead to accurate diagnosis, appropriate molecular genetic testing and genetic counseling.
Collapse
|
3
|
Abstract
The presence of melanin pigment within the iris is responsible for the visual impression of human eye colouration with complex patterns also evident in this tissue, including Fuchs' crypts, nevi, Wolfflin nodules and contraction furrows. The genetic basis underlying the determination and inheritance of these traits has been the subject of debate and research from the very beginning of quantitative trait studies in humans. Although segregation of blue-brown eye colour has been described using a simple Mendelian dominant-recessive gene model this is too simplistic, and a new molecular genetic perspective is needed to fully understand the biological complexities of this process as a polygenic trait. Nevertheless, it has been estimated that 74% of the variance in human eye colour can be explained by one interval on chromosome 15 that contains the OCA2 gene. Fine mapping of this region has identified a single base change rs12913832 T/C within intron 86 of the upstream HERC2 locus that explains almost all of this association with blue-brown eye colour. A model is presented whereby this SNP, serving as a target site for the SWI/SNF family member HLTF, acts as part of a highly evolutionary conserved regulatory element required for OCA2 gene activation through chromatin remodelling. Major candidate genes possibly effecting iris patterns are also discussed, including MITF and PAX6.
Collapse
Affiliation(s)
- Richard A Sturm
- Melanogenix Group, Institute for Molecular Bioscience, The University of Queensland, Brisbane, Qld, Australia.
| | | |
Collapse
|
4
|
Wang Y, Guo X, Wei A, Zhu W, Li W, Lian S. Identification of a novel mutation in a Chinese family with X-linked ocular albinism. Eur J Ophthalmol 2009; 19:124-8. [PMID: 19123159 DOI: 10.1177/112067210901900118] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE The purpose of the study was to evaluate the GPR143 gene (G-protein coupled receptor 143) in a Chinese three-generation family with OA1, including four carriers and a proband with clinical features of X-linked ocular albinism. METHODS The proband underwent a detailed ophthalmologic evaluation. Blood samples of family members were obtained and genomic DNA isolated. Mutational analysis by SSCP and direct sequencing of the GPR143 gene was used to screen all nine exons including the intron/exon junctions. The novel mutation c.943G>T (p.G315X) found in the study was confirmed by DHPLC to exclude the possibility of polymorphism. RESULTS Ophthalmic features of the proband were characteristic of X-linked ocular albinism. The authors identified a novel nonsense mutation p.G315X on exon 8 that was not found in 100 non-albinism subjects by DHPLC. This novel mutation in the GPR143 gene is predicted to subject to nonsense mediated decay. CONCLUSIONS The novel mutation p.G315X in the OA1 gene was identified in a Chinese family with ocular albinism, which is predicted to generate a premature stop codon. These findings extend the mutational spectrum of GPR143 gene and will be useful for gene diagnosis and genetic counseling in Chinese OA1 patients.
Collapse
Affiliation(s)
- Y Wang
- Department of Dermatology, Xuan Wu Hospital, Capital Medical University, Beijing, China
| | | | | | | | | | | |
Collapse
|
5
|
Kutzbach B, Summers CG, Holleschau AM, King RA, MacDonald JT. The prevalence of attention-deficit/hyperactivity disorder among persons with albinism. J Child Neurol 2007; 22:1342-7. [PMID: 18174549 DOI: 10.1177/0883073807307078] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Attention-deficit/hyperactivity disorder (ADHD) is a common diagnosis in children and adults. Human albinism is an uncommon genetic condition associated with visual impairment that may affect behavior. To determine if there is a relationship between albinism and ADHD, the prevalence of ADHD was examined among 78 children (age range, 4-18 years) and among 44 adults (age range, 19-79 years) with ocular or oculocutaneous albinism. ADHD was diagnosed in the pediatric population using a combination of Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) criteria, Conners' Parent Rating Scale, and physician observation. Adults were diagnosed using the Utah criteria for ADHD as confirmed by physician history and interview. Seventeen children (22.7% [17 of 75]) (3 children with existing diagnoses of pervasive developmental disorder were identified but were not included in the data analysis) and 3 adults (6.8%) met the criteria for ADHD. The combined hyperactivity and impulsivity subtype of ADHD was most common, accounting for 50% of the diagnoses. Binocular best-corrected visual acuity and genetic type of albinism were not found to correlate with a diagnosis of ADHD. The prevalence of ADHD among children and adults with albinism is more frequent than that reported among the general population and is not related to binocular best-corrected visual acuity.
Collapse
Affiliation(s)
- Beth Kutzbach
- Department of Pediatrics, University of Minnesota, Minneapolis 55455, USA
| | | | | | | | | |
Collapse
|
6
|
Liu JY, Ren X, Yang X, Guo T, Yao Q, Li L, Dai X, Zhang M, Wang L, Liu M, Wang QK. Identification of a novel GPR143 mutation in a large Chinese family with congenital nystagmus as the most prominent and consistent manifestation. J Hum Genet 2007; 52:565-570. [PMID: 17516023 DOI: 10.1007/s10038-007-0152-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2007] [Accepted: 04/02/2007] [Indexed: 11/24/2022]
Abstract
Congenital nystagmus is characterized by involuntary, rhythmical, repeated oscillations of one or both eyes. We studied a large Chinese family with nystagmus as a prominent and consistent manifestation phenotype in nine patients to map and identify a disease-causing gene for nystagmus. X-linked recessive inheritance was observed in the family, and foveal hypoplasia was detected in some of the nine patients. The disease gene was mapped to an approximately 10.6 Mb region flanked by DXS996 and DXS7593 on Xp22 with a significant peak multipoint LOD score. Analysis of 21 candidate genes in the region revealed a novel p.S89F mutation in the second transmembrane domain of GPR143, a G protein-coupled receptor which causes ocular albinism when mutated. All male patients in the family were hemizygous for the mutation; the female carriers were heterozygous for the mutation. The p.S89F mutation was not identified in 100 normal females or 100 normal males. Our results indicate that a mutation in the GPR143 gene can cause a variant form of ocular albinism, with congenital nystagmus as the most prominent and only consistent finding in all patients in this Chinese family. These results expand the spectrum of clinical phenotypes associated with GPR143 mutations.
Collapse
Affiliation(s)
- Jing Yu Liu
- Center for Human Genome Research and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, People's Republic of China
| | - Xiang Ren
- Center for Human Genome Research and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, People's Republic of China
| | - Xiufeng Yang
- Development of Proof-Testing, Renmin Hospital of Tanghe, Tanghe, Henan, People's Republic of China
| | - Tangying Guo
- Development of Proof-Testing, Renmin Hospital of Tanghe, Tanghe, Henan, People's Republic of China
| | - Qi Yao
- Center for Human Genome Research and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, People's Republic of China
| | - Lin Li
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic/NE40, Cleveland, OH, 44195, USA
| | - Xiaohua Dai
- Center for Human Genome Research and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, People's Republic of China
| | - Mingchang Zhang
- Department of Ophthalmology, Union Hospital, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Lejin Wang
- Eye Center, Peking University, Beijing, People's Republic of China
| | - Mugen Liu
- Center for Human Genome Research and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, People's Republic of China.
| | - Qing K Wang
- Center for Human Genome Research and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, People's Republic of China.
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic/NE40, Cleveland, OH, 44195, USA.
| |
Collapse
|