Regional variation in blindness in children due to microphthalmos, anophthalmos and coloboma

Hornby, Stella J; Gilbert, Clare; Rahi, Jugnoo S; Sil, Asim Kumar; Xiao, Yungao; Dandona, Lalit; Foster, Allen

doi:10.1076/0928-6586(200006)721-zft127

Cited by 62 publications

(41 citation statements)

References 15 publications

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“…21 Severe visual loss due to congenital abnormalities of the globe is estimated to affect between 0.4 and 16.2/100 000 children in the countries studied. 24 More research is needed to determine the contributing factors to these conditions.…”

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confidence: 99%

Childhood blindness and severe visual impairment in Malaysia: a nationwide study

Patel

Tajunisah

Gilbert

et al. 2011

Eye

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Aim To determine the causes of childhood blindness and severe visual impairment (BL/SVI) in schools for the blind in Malaysia. Methods All children r15years attending 24 schools for the blind throughout the country were examined using the WHO Prevention of Blindness Programme (WHO/PBL) eye examination record for children, and visual loss was classified according to the International Classification of Disease (ICD). Results In all, 469 children were examined, of whom 448 (95.6%) had BL/SVI. The major causes of visual loss were retinal disorders (n ¼ 148, 33%; mainly retinopathy of prematurity (n ¼ 78, 17.4%)), cataract/ pseudophakia/aphakia (n ¼ 77, 17.2%), and anomalies affecting the whole globe. (n ¼ 86, 19.2%). The major underlying etiology was undetermined (n ¼ 193, 43.1%), followed by hereditary factors, 21.7% (mainly retinal dystrophies), and perinatal factors, 20.5%. More than 34 (7.6%) cases were considered potentially preventable and 192 (42.9%) potentially treatable. Conclusion Diseases of the retina are the major cause of visual impairment, with retinopathy of prematurity being an important avoidable cause. This reflects expansion of neonatal services in Malaysia, and improved survival of very low birth weight and preterm babies. Lens-related causes of visual impairment reflect the need to further improve pediatric ophthalmology services in Malaysia.

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confidence: 99%

Childhood blindness and severe visual impairment in Malaysia: a nationwide study

Patel

Tajunisah

Gilbert

et al. 2011

Eye

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“…Symptoms of vitamin-A deficiency become first noticeable in the eye: an early sign of postnatal deficiency is night blindness, and eye malformations are the most sensitive indicator of fetal vitamin-A deficiency (Wilson et al, 1953). The eye is the only organ identified so far for which inherited developmental defects have been linked to environmental vitamin-A disturbances: the frequency of severe familial eye malformations is several times higher in regions where vitamin-A deficiency is endemic compared to richer countries (Hornby et al, 2000(Hornby et al, , 2001(Hornby et al, , 2003. This reflects the very high RA levels in the early embryonic eye, which regulate the expression of many early eye genes.…”

Section: Eye Is Central To Retinoidsmentioning

confidence: 98%

Retinoids, eye development, and maturation of visual function

et al. 2006

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Vitamin A is known to be critical for the beginning of eye development as well as for photoreception in the functional retina. Hardly anything, however, is known about whether retinoic acid (RA)-regulated gene expression also plays a role in the long intervening period, during which the neurobiological retinal structure takes shape. The eye contains a highly intricate architecture of RA-synthesizing (RALDH) and degrading (CYP26) enzymes. Whereas the RALDHs are integrated in the early molecular mechanisms through which the dorso-ventral retina organization is established, the CYP26 enzymes are not necessary for this process and no molecular targets that match their retinal expression pattern have yet been identified. In this article we describe that CYP26 expression in the mouse is most distinctive during later stages of retina formation. Throughout development CYP26A1 degrades RA in a horizontal region that extends across the retina, but during later embryonic and postnatal retina maturation this function is reinforced by another enzyme, CYP26C1. RA applications at this stage do not affect the RALDHs but cause differential changes in CYP26 expression: Cyp26a1 is up-regulated, but more rapidly by 9-cis than all-trans RA, Cyp26c1 is down-regulated, and Cyp26b1, which is undetectable in the normal mouse retina, is strongly activated in retinal ganglion cells. The dynamic regulation in RA-difference patterns by the CYP26 enzymes may set up spatial constellations for expression of genes involved in formation of retinal specializations for higher acuity vision, which are known to form over a prolonged period late in retina development.

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“…Developmental eye anomalies, including anophthalmia and microphthalmia, are responsible for up to 25% of childhood visual impairment [Hornby et al, 1999[Hornby et al, , 2000. Clinical severity is variable, ranging from at its most severe, clinical anophthalmia (absent eye), through microphthalmia (congenitally small eye), to anomalies that only affect specific substructures of the eye.…”

Section: Introductionmentioning

confidence: 99%

Seeing clearly: the dominant and recessive nature ofFOXE3in eye developmental anomalies

et al. 2009

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FOXE3 is a lens-specific transcription factor with a highly conserved forkhead domain previously implicated in congenital primary aphakia and anterior segment dysgenesis. Here, we identify new recessive FOXE3 mutations causative for microphthalmia, sclerocornea, primary aphakia, and glaucoma in two extended consanguineous families by SNP array genotyping followed by a candidate gene approach. Following an additional screen of 236 subjects with developmental eye anomalies, we report two further novel heterozygous mutations segregating in a dominant fashion in two different families. Although the dominant mutations were penetrant, they gave rise to highly variable phenotypes including iris and chorioretinal colobomas, Peters' anomaly, and isolated cataract (cerulean type and early onset adult nuclear and cortical cataract). Using in situ hybridization in human embryos, we demonstrate expression of FOXE3 restricted to lens tissue, predominantly in the anterior epithelium, suggesting that the extralenticular phenotypes caused by FOXE3 mutations are most likely to be secondary to abnormal lens formation. Our findings suggest that mutations in FOXE3 can give rise to a broad spectrum of eye anomalies, largely, but not exclusively related to lens development, and that both dominant and recessive inheritance patterns can be represented. We suggest including FOXE3 in the diagnostic genetic screening for these anomalies.

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Regional variation in blindness in children due to microphthalmos, anophthalmos and coloboma

Abstract: Major congenital abnormalities of the globe are important causes of severe visual loss in children, particularly in Asian countries. Further research into etiology is warranted in order to plan prevention programs.

Cited by 62 publications

References 15 publications

Childhood blindness and severe visual impairment in Malaysia: a nationwide study

Childhood blindness and severe visual impairment in Malaysia: a nationwide study

Retinoids, eye development, and maturation of visual function

Seeing clearly: the dominant and recessive nature ofFOXE3in eye developmental anomalies

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