Korean J Ophthalmol.  2014 Aug;28(4):343-350.

Comparative Quantification of Plasma TDRD7 mRNA in Cataract Patients by Real-time Polymerase Chain Reaction

• Kim ST
• Chun JW
• Park G
• Koh JW

Abstract

PURPOSE
To investigate the relationship between plasma TDRD7 mRNA and lens transparency, and to evaluate plasma TDRD7 mRNA as a potential marker for cataracts and its sub-type by quantitatively analyzing human peripheral blood.
METHODS
Plasma RNA was extracted from 40 patients with cataracts, and 30 normal controls of matched age and gender. Blood cholesterol and fasting glucose were measured, and the RNA extracted from the sample was synthesized into cDNA. After polymerase chain reaction, the results were compared after quantifying the TDRD7 mRNA using ABL1 mRNA for normalization. We analyzed the relative gene expression data via the DeltaDeltaCt method.
RESULTS
The normalized 2(-DeltaDeltaCt) of plasma TDRD7 mRNA based on ABL1 mRNA was 1.52 ± 0.63 in the case of the control group and 1.05 ± 0.34 in the case of the cataract patients, and the TDRD7 expression level of the cataract patients was lower than that of the control group (p = 0.048). The comparison of the genetic values of different types of cataracts demonstrated that the TDRD7 expression level of the cortical type and mixed type were lower than those of the nuclear type and posterior subcapsular opacity type (p = 0.017).
CONCLUSIONS
Human cataracts and the TDRD7 gene loss-of-function mutations are strongly causally related, as the expression level of plasma TDRD7 mRNA in patients with cataracts was statistically significantly lower than in the normal control group.

Keyword

Cataract; Real-time polymerase chain reaction; TDRD7

MeSH Terms

Adolescent
Adult
Aged
Aged, 80 and over
Cataract/*blood
Child
Female
Gene Expression Regulation/*physiology
Humans
Male
Middle Aged
Proto-Oncogene Proteins c-abl/genetics
RNA, Messenger/*blood
Real-Time Polymerase Chain Reaction
Ribonucleoproteins/*genetics
Proto-Oncogene Proteins c-abl
RNA, Messenger
Ribonucleoproteins

Figure

• 

  Fig. 1 Comparison of gene expression of ABL1 and TDRD7 genes in cataract group versus normal group by quantitative real-time reverse transcription polymerase chain reaction (RT-PCR). Amplification curves for A) ABL1, B) TDRD7 (normal group), and C) TDRD7 (cataract group). The threshold level is given by a horizontal line. The cycle at which the mean amplification curve of ABL1 or TDRD7 real-time RT-PCRs crosses the threshold (cycle threshold value) is indicated by a vertical line. RFU = relative fluorescence units.

• 

  Fig. 2 Normalized plasma TDRD7 mRNA in the patient group amount relative to that in normal control group. Fold change was expressed as 2-ΔΔCt (ΔCt [TDRD7-ABL1] of each case-average ΔCt [average TDRD7 Ct-average ABL1 Ct] of normal control group). Ct = cycle threshold.

• 

  Fig. 3 Visualization for the comparison of the 2-ΔΔCt value according to the type of cataract. Fold change was expressed as 2-ΔΔCt (ΔCt [TDRD7-ABL1] of each case-average ΔCt [average TDRD7 Ct-average ABL1 Ct] of normal control group). PSC = posterior subcapsular; Ct = cycle threshold.

• 

  Fig. 4 Correlation analysis between age and TDRD7 gene expression levels in the blood of the normal group by polymerase chain reaction.

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