Cataract development in a young patient with lathosterolosis: a clinicopathologic case report

Comparative quantification of plasma TDRD7 mRNA in cataract patients by real-time polymerase chain reaction

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 ΔΔCt method.

Results

The normalized 2^-ΔΔCt 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.

Malformation syndromes caused by disorders of cholesterol synthesis

Cholesterol homeostasis is critical for normal growth and development. In addition to being a major membrane lipid, cholesterol has multiple biological functions. These roles include being a precursor molecule for the synthesis of steroid hormones, neuroactive steroids, oxysterols, and bile acids. Cholesterol is also essential for the proper maturation and signaling of hedgehog proteins, and thus cholesterol is critical for embryonic development. After birth, most tissues can obtain cholesterol from either endogenous synthesis or exogenous dietary sources, but prior to birth, the human fetal tissues are dependent on endogenous synthesis. Due to the blood-brain barrier, brain tissue cannot utilize dietary or peripherally produced cholesterol. Generally, inborn errors of cholesterol synthesis lead to both a deficiency of cholesterol and increased levels of potentially bioactive or toxic precursor sterols. Over the past couple of decades, a number of human malformation syndromes have been shown to be due to inborn errors of cholesterol synthesis. Herein, we will review clinical and basic science aspects of Smith-Lemli-Opitz syndrome, desmosterolosis, lathosterolosis, HEM dysplasia, X-linked dominant chondrodysplasia punctata, Congenital Hemidysplasia with Ichthyosiform erythroderma and Limb Defects Syndrome, sterol-C-4 methyloxidase-like deficiency, and Antley-Bixler syndrome.