P497 Opsin

SALSA MLPA Probemix P497 Opsin detects copy number variations in the OPN1LW and OPN1MW genes and their locus control region (LCR).

Specifications

Contents: 32 MLPA probes, including 6 probes for OPN1LW, 6 probes for OPN1MW, 2 probes for the LCR, and 10 probes that target both OPN1LW and OPN1MW of which 1 detects the wild-type sequence of the c.607T>C (p.Cys203Arg) mutation (more details).

Tissue: human genomic DNA.

Application: research on cone photoreceptor disorders, including red-green colour blindness, deuteranopia, protanopia, X-linked cone dystrophy, blue cone monochromatism, and Bornholm eye disease.

For research use only (RUO). Not for use in diagnostics.

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List Prices Documentation

General information

The SALSA MLPAProbemix P497 Opsin is a research use only (RUO) assay for the detection of deletions or duplications in the OPN1LW and OPN1MW genes and their locus control region (LCR). This probemix can also be used to detect the wild type sequence of the p.Cys203Arg (c.607T>C) mutation in OPN1LW and OPN1MW.

Copy number changes in the X-chromosomal genes OPN1LW and OPN1MW result in a number of cone photoreceptor disorders, including red-green colour blindness, deuteranopia, protanopia, X-linked cone dystrophy, blue cone monochromatism, and Bornholm eye disease. Red-green colour blindness is the most common form and affects males much more often than females. Among populations with Northern European ancestry, red-green colour blindness occurs in about 1 in 12 males and 1 in 200 females. Affected individuals have trouble distinguishing between shades of red, yellow, and green. The majority of affected individuals are thought to have a stable condition, however, some develop evidence of progression with increasing visual acuity loss, macular atrophy, retinal pigmentation, and electrophysiological evidence of S cone and rod involvement (Gardner et al. 2014; Gardner 2016).

The close proximity (~23 kb) and extensive sequence identity (96-98%) of the OPN1LW and OPN1MW genes promotes meiotic mispairing of the genes and non-homologous recombination, and less commonly gene conversion events. This might lead to the formation of a hybrid pigment gene that contains part of both OPN1LW and OPN1MW. Also, some unusual combinations of individually benign nucleotide variations in exon 3 that can arise from recombination between OPN1LW and OPN1MW are associated with vision disorders. These pathogenic SNP interchange haplotypes include variants abbreviated as LIAVA, LVAVA and MIAVA for the amino acids specified by positions p.153, p.171, p.174, p.178, and p.180 where L is leucine, V is valine, I is isoleucine, A is alanine and M is methionine. These variants have shown to result in aberrant splicing and exon 3 skipping (Gardner et al. 2014; Greenwald et al. 2017; Verelli et al. 2004). Because of the frequent exchange, X chromosomes can have up to five OPN1MW copies, whereas individuals rarely have more than one OPN1LW copy per X chromosome.

Figure 1. Schematic representation of the position of the OPN1LW and OPN1MW genes on chromosome Xq28. Adapted from Gardner JC et al. (2009) via https://www.blueconemonochromacy.org/molecular-genetics/.

Transcription of the OPN1LW and OPN1MW genes is regulated by a nearby region of DNA, known as the LCR (Figure 1). Only the two opsin pigment genes nearest the LCR, generally the OPN1LW gene and the first copy of the OPN1MW gene, are active in the retina and contribute to colour vision. Figure 2 gives an overview of the copy number changes and variants in OPN1LW and OPN1MW related to disease.

Figure 2. Changes in OPN1LW and OPN1MW leading to different visual disorders. Only the first amino acid of the exon 3 SNP interchangeable haplotypes (e.g. LIAVA) can be detected by this probemix, and the p.W177R mutation cannot be detected. See the product description for more information. Adapted from Haer-Wigman L. (personal communication).

The OPN1LW gene (6 exons) spans ~14.8 kb of genomic DNA and the OPN1MW gene (6 exons) spans ~14.3 kb of genomic DNA, both are located on chromosome Xq28.

More information is available at https://ghr.nlm.nih.gov/condition/color-vision-deficiency.

Probe targets

Figure 3 shows the location of the probes included in this probemix.

Figure 3. The location of probes targeting the genes OPN1LW (red) and OPN1MW (green) and the probes recognizing both genes (orange) and the LCR (yellow). The numbers above/below the arrows represent the length (in nt) of the respective probes. The 174 nt probe detects the wild-type sequence of the c.607T>C (p.Cys203Arg) mutation.

Regulatory status

SALSA MLPA Probemix P497 Opsin is for research use only (RUO) in all territories.

SALSA Sample DNA for this product

SALSA Reference Selection DNA SD098 can be used to aid in the selection of suitable reference samples for the P497 Opsin probemix. Reference Selection DNA can only be used in initial experiments on DNA samples from healthy individuals from your sample collection with the intention to identify suitable reference samples. SD098 cannot be used as a reference sample in subsequent experiments.

A vial of SALSA Reference Selection DNA SD098 is included with every order of the P497 Opsin probemix, but it is possible to order additional vials separately.

For more information, see the product description.

Product documentation

List prices

Product

Item no.

Description

Technology

Price

P497-025R

SALSA MLPA Probemix P497 Opsin – 25 rxn

MLPA

€ 286.00

P497-050R

SALSA MLPA Probemix P497 Opsin – 50 rxn

MLPA

€ 560.00

P497-100R

SALSA MLPA Probemix P497 Opsin – 100 rxn

MLPA

€ 1096.00

Required reagents

A general SALSA MLPA Reagent Kit is required for MLPA experiments (to be ordered separately).

Item no.

Description

Technology

Price

EK1-FAM

SALSA MLPA Reagent Kit – 100 rxn – FAM (6 vials)

MLPA MS-MLPA

€ 348.00

EK1-CY5

SALSA MLPA Reagent Kit – 100 rxn – Cy5 (6 vials)

MLPA MS-MLPA

€ 348.00

EK5-FAM

SALSA MLPA Reagent Kit – 500 rxn – FAM (5×6 vials)

MLPA MS-MLPA

€ 1600.00

EK5-CY5

SALSA MLPA Reagent Kit – 500 rxn – Cy5 (5×6 vials)

MLPA MS-MLPA

€ 1600.00

EK20-FAM

SALSA MLPA Reagent Kit – 2000 rxn – FAM (5×6 vials)

MLPA MS-MLPA

€ 6152.00

Sample DNAs (included)

A vial is included with every order of this probemix, but additional vials can also be purchased separately.

Item no.

Description

Technology

Price

SD098

SALSA Binning DNA SD098 – 6 rxn

MLPA

€ 24.15

Price details & ordering

The prices above are list prices for direct orders from MRC Holland. Contact us for a quote that takes discounts and additional costs (such as shipping costs) into account. Different prices apply for orders through one of our sales partners; contact your local supplier for a quote.

More information about ordering & prices

Positive samples

Inclusion of a positive sample is usually not required, but can be useful for the analysis of your experiments. MRC Holland has very limited access to positive samples and cannot supply such samples. We recommend using positive samples from your own collection. Alternatively, you can use positive samples from an online biorepository, such as the Coriell Institute.

We have no information about specific commercially available positive samples that can be used with this product.