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PAX6 gene analysis in irido-fundal coloboma.

Kumar K, Tanwar M, Naithani P, Insaan R, Garg S, Venkatesh P, Dada R - Mol. Vis. (2011)

Bottom Line: This study expands the SNP spectrum of PAX6, only rare variations which are not causative have been found.Since this is a pilot study in the north Indian population, results should be confirmed in different populations by similar studies.Familial cases are required for determining the underlying genetic loci accounting for this clinical phenotype and may lead to better understanding of disease pathogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.

ABSTRACT

Purpose: To screen the paired box gene 6 (PAX6) gene in irido-fundal coloboma.

Methods: The entire coding region of PAX6 including intron-exon boundaries was amplified from cases (n=30) and controls (n=30). All sequences were analyzed against the ensemble sequence (ENSG00000007372) for PAX6.

Results: DNA sequence analysis of patients and controls revealed a total of three nucleotide changes (g.31815391Cytosine>Thymine; Glycine72Glycine and g.31812215Thymine>Guanine) of which one was neutral/synonymous change and the remaining two were intronic changes. Of these 3 changes, 2 were novel and one was already reported change. All these changes were non-pathogenic, according to in silico analysis.

Conclusions: In our study no pathogenic PAX6 mutation were identified. This suggests involvement of other coloboma genes. This study expands the SNP spectrum of PAX6, only rare variations which are not causative have been found. Since this is a pilot study in the north Indian population, results should be confirmed in different populations by similar studies. Familial cases are required for determining the underlying genetic loci accounting for this clinical phenotype and may lead to better understanding of disease pathogenesis.

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Related in: MedlinePlus

Fundus photograph in type V coloboma.
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f3: Fundus photograph in type V coloboma.

Mentions: Congenital malformations of the eyeball appear to occur more frequently in certain countries like India and Sri Lanka, accounting for approximately 25% of cases of visual impairment and blindness [1]. Ocular coloboma is a congenital, common, and heterogeneous malformation which includes a spectrum of anomalies ranging from iris coloboma to clinical anophthalmos. Ocular coloboma, as an isolated defect, is usually inherited as an autosomal dominant disorder, although autosomal recessive inheritance also occurs. Coloboma is a hole in one of the structures of the eye, such as the iris, retina, choroid, or optic disc. If coloboma is present both in iris and retina it is known as irido-fundal coloboma. According to coloboma location in the retina and whether it involves the optic nerve or not, coloboma is classified into six types by Gopal [2]: (I) this involves the optic nerve and is the biggest type of coloboma (Figure 1). Vision is generally quite poor in this type; (II) involves the optic nerve but it is smaller than type I, so vision is poor but not as bad as in type I coloboma; (III) this just misses the optic nerve (Figure 2) so vision can be quite good. However if associated with increased axial length and resulting high myopic refractive error (spectacle number) the vision can be decreased; (IV) this coloboma involves only the optic nerve but not much retina that surrounds it. Vision can be good to average depending on how much the optic nerve is distorted; (V) this coloboma is in the periphery and does not involve the optic nerve as well as the main area of the retina (Figure 3). As far as vision is considered it is quite good in this type and any problem in vision might not be noticed by the patient; (VI) these are partially aborted attempts at forming coloboma. Vision is unaffected in this type of coloboma.


PAX6 gene analysis in irido-fundal coloboma.

Kumar K, Tanwar M, Naithani P, Insaan R, Garg S, Venkatesh P, Dada R - Mol. Vis. (2011)

Fundus photograph in type V coloboma.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3108901&req=5

f3: Fundus photograph in type V coloboma.
Mentions: Congenital malformations of the eyeball appear to occur more frequently in certain countries like India and Sri Lanka, accounting for approximately 25% of cases of visual impairment and blindness [1]. Ocular coloboma is a congenital, common, and heterogeneous malformation which includes a spectrum of anomalies ranging from iris coloboma to clinical anophthalmos. Ocular coloboma, as an isolated defect, is usually inherited as an autosomal dominant disorder, although autosomal recessive inheritance also occurs. Coloboma is a hole in one of the structures of the eye, such as the iris, retina, choroid, or optic disc. If coloboma is present both in iris and retina it is known as irido-fundal coloboma. According to coloboma location in the retina and whether it involves the optic nerve or not, coloboma is classified into six types by Gopal [2]: (I) this involves the optic nerve and is the biggest type of coloboma (Figure 1). Vision is generally quite poor in this type; (II) involves the optic nerve but it is smaller than type I, so vision is poor but not as bad as in type I coloboma; (III) this just misses the optic nerve (Figure 2) so vision can be quite good. However if associated with increased axial length and resulting high myopic refractive error (spectacle number) the vision can be decreased; (IV) this coloboma involves only the optic nerve but not much retina that surrounds it. Vision can be good to average depending on how much the optic nerve is distorted; (V) this coloboma is in the periphery and does not involve the optic nerve as well as the main area of the retina (Figure 3). As far as vision is considered it is quite good in this type and any problem in vision might not be noticed by the patient; (VI) these are partially aborted attempts at forming coloboma. Vision is unaffected in this type of coloboma.

Bottom Line: This study expands the SNP spectrum of PAX6, only rare variations which are not causative have been found.Since this is a pilot study in the north Indian population, results should be confirmed in different populations by similar studies.Familial cases are required for determining the underlying genetic loci accounting for this clinical phenotype and may lead to better understanding of disease pathogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.

ABSTRACT

Purpose: To screen the paired box gene 6 (PAX6) gene in irido-fundal coloboma.

Methods: The entire coding region of PAX6 including intron-exon boundaries was amplified from cases (n=30) and controls (n=30). All sequences were analyzed against the ensemble sequence (ENSG00000007372) for PAX6.

Results: DNA sequence analysis of patients and controls revealed a total of three nucleotide changes (g.31815391Cytosine>Thymine; Glycine72Glycine and g.31812215Thymine>Guanine) of which one was neutral/synonymous change and the remaining two were intronic changes. Of these 3 changes, 2 were novel and one was already reported change. All these changes were non-pathogenic, according to in silico analysis.

Conclusions: In our study no pathogenic PAX6 mutation were identified. This suggests involvement of other coloboma genes. This study expands the SNP spectrum of PAX6, only rare variations which are not causative have been found. Since this is a pilot study in the north Indian population, results should be confirmed in different populations by similar studies. Familial cases are required for determining the underlying genetic loci accounting for this clinical phenotype and may lead to better understanding of disease pathogenesis.

Show MeSH
Related in: MedlinePlus