A kindred with fish eye disease, corneal opacities, marked high-density lipoprotein deficiency, and statin therapy.

A kindred affected with fish eye disease (FED) from Oklahoma is reported. Two probands with corneal opacification had mean levels of high-density lipoprotein (HDL) cholesterol (C), apolipoprotein (apo) A-I, and apoA-I in very large alpha-1 HDL particles that were 9%, 17%, and 5% of normal, whereas their parents and 1 sibling had values that were 61%, 77%, and 72% of normal. The probands had no detectable lipoprotein-X, and had mean low-density lipoprotein cholesterol (LDL-C) and triglyceride levels that were elevated. Their mean lecithin cholesterol acyltransferase (LCAT) activities, cholesterol esterification rates, and free cholesterol levels were 8%, 42%, and 258% of normal, whereas their parents and 1 sibling had values that were 55%, 49%, and 114% of normal. The defect was due to 1 common variant in the LCAT gene in exon 1: c101t causing a proline34leucine substitution and a novel mutation c1177t causing a threonine37methionine substitution, with the former variant being found in the father and 1 sibling, and the latter mutation being found in the mother, and both mutations being present in the 2 probands. FED is distinguished from familial LCAT deficiency (FLD) by the lack of anemia, splenomegaly, and renal insufficiency as well as normal or increased LDL-C. Both FLD and FED cases have marked HDL deficiency and corneal opacification, and FED cases may have premature coronary heart disease in contrast to FLD cases. Therapy, using presently available agents, in FED should be to optimize LDL-C levels, and 1 proband responded well to statin therapy. The investigational use of human recombinant LCAT as an enzyme source is ongoing.

Hypergammaglobulinemia and corneal opacities in patients with human T-cell lymphotrophic virus type-1.

PURPOSE: To investigate the relationship between serum immunoglobulin levels and corneal opacities in a cohort of patients with human T-cell lymphotrophic virus type-1 (HTLV-1). DESIGN: Retrospective case series. METHODS: Complete ophthalmologic examination was performed on 44 patients with HTLV-1 infection (25 patients with adult T-cell leukemia/lymphoma [ATL], 18 patients with HTLV-1 that was associated myelopathy/tropical spastic paraparesis [HAM/TSP], and one patient who was asymptomatic). Corneal opacities were described by shape, size, color, and location. Serum immunoglobulin (Ig) levels (IgG, IgM, and IgA) were measured by nephelometry. RESULTS: Corneal opacities were identified in 15 of 25 patients (60%) with ATL and five of 18 patients (28%) with HAM/TSP. The prevalence of corneal opacities was associated statistically with elevated IgG level (P = .023) in patients with ATL, but not in patients with HAM/TSP (P > .99). CONCLUSION: Although the mechanism remains unclear, hypergammaglobulinemia is associated with the development of the corneal opacities in patients of African descent with ATL.

Central corneal mosaic opacities in Schnyder's crystalline dystrophy.

PURPOSE: To report an unusual presentation of Schnyder's corneal crystalline dystrophy (SCCD), sharing the feature of central corneal mosaic opacities. DESIGN: Observational case report. METHODS: A 51-year-old man and his family members were examined. Investigations included slit-lamp biomicroscopy, radiography of knee joint, plasma lipid level, and genotyping of the SCCD candidate region in chromosome 1p34.1-1p36. RESULTS: A symmetric, central, disciform, full-thickness opacity was seen in both corneas of the patient. The opacities appeared in a mosaic pattern, instead of collections of crystals or a diffuse haze as typically detected in SCCD. Small clumps of crystalline deposits and arcus lipoides were also observed. Systemically, hyperlipidemia and bilateral genu valgus were identified. He had 2 daughters, and both of them had bilateral corneal crystalline deposits and genu valgus. No other family members had findings suggesting SCCD. The genetic study demonstrated that all of the affected individuals shared a common haplotype within the region of previously reported SCCD locus. However, 1 unaffected sibling of the proband also had the same haplotype. CONCLUSIONS: Central corneal mosaic opacities may be another variant of SCCD.

Classical LCAT deficiency resulting from a novel homozygous dinucleotide deletion in exon 4 of the human lecithin: cholesterol acyltransferase gene causing a frameshift and stop codon at residue 144.

Lecithin: cholesterolacyltransferase (LCAT) transacylates the fatty acid at the sn-2 position of lecithin to the 3beta-OH group of cholesterol forming lysolecithin and the majority of cholesteryl ester found in plasma. LCAT participates in the reverse cholesterol transport pathway in man where it esterifies tissue-derived cholesterol following efflux from peripheral cells into HDL. Only 38 unique mutations in the human LCAT gene have been reported worldwide. Our French female proband presented with corneal opacity and no detectable plasma LCAT activity using either endogenous or exogenous assays. Her total plasma cholesterol and HDL cholesterol were low (2.34 mmol/l and 0.184 mmol/l, respectively) with a very high cholesterol/cholesteryl ester molar ratio (10.9:1). Plasma triglycerides were 0.470 mmol/l with low apo B (40.5 mg/dl), apo A-I (14.7 mg/dl), apo A-II (6.8 mg/dl) and apo E (2.1 mg/dl) levels. Plasma lipoprotein analysis by ultracentrifugation showed very low HDL concentrations and a characteristic shift of the lipoprotein profile towards larger, less dense particles. No proteinuria, renal dysfunction or signs of atherosclerosis were noted at age 45. Sequence analysis of her LCAT gene showed a novel homozygous TG-deletion at residues 138-139 that resulted in a frameshift causing the generation of a stop codon and premature termination of the LCAT protein at amino acid residue 144. Western blotting of the patient's plasma using a polyclonal IgY primary antibody against human LCAT failed to demonstrate the presence of a truncated LCAT protein. A 53 bp mismatched PCR primer was designed to generate an Fsp 1 restriction site in the wild type sequence of exon 4 where the mutation occurred. The 155 bp PCR product from the wild type allele produced a 103 bp and 52 bp fragment with Fsp 1 and no cleavage products with the mutant allele thus permitting rapid screening for this novel mutation.

Two novel molecular defects in the LCAT gene are associated with fish eye disease.

A 53-year-old man with a severely reduced HDL cholesterol level, dense corneal opacities, normal renal function, and premature coronary artery disease was investigated together with 16 members of his family. The proband was diagnosed with fish eye disease. As in previously reported patients with fish eye disease, the endogenous plasma cholesterol esterification rate was near normal, yet lecithin:cholesterol acyltransferase (LCAT) activity was almost absent when measured with exogenous HDL analogues used as substrate. Direct sequencing of the LCAT gene revealed two novel missense mutations in exon 1 and exon 4, resulting in the substitution of Pro10 with Gln (P10Q) and Arg135 with Gln (R135Q), respectively. Both missense mutations were located on different alleles. Genetic analysis by polymerase chain reaction revealed 4 carriers of the P10Q and 3 carriers of the R135Q defect. Functional assessment of both missense mutations revealed that when exogenous HDL analogues were used as substrate, the specific activity of rLCAT p10Q was 18% of wild type (WT); however, when LDL was used as substrate, the activity was 146% of WT. By contrast, rLCATR135Q was inactive against both substrates. Thus, we conclude that the LCATR135D mutation is causative for complete LCAT deficiency and that the clinical phenotype of fish eye disease seen in this patient is due to the Pro10 mutation. The presence of premature coronary artery disease in the absence of other risk factors in this new case of fish eye disease raises questions regarding the risk of atherosclerosis, which has previously been reported to be nonexistent.

Spontaneous development of corneal crystalline deposits in MRL/Mp mice.

PURPOSE: The presence of corneal opacities associated with dacryoadenitis and lacrimal gland destruction has led investigators to consider MRL/Mp mice as models for band keratopathy and Sjögren syndrome. In this study, the authors examined the time course of the corneal opacification and investigated whether the opacities were associated with altered serum levels of parathyroid hormone, calcium, and phosphorus, as well as quantitative and qualitative differences in tear production. METHODS: Corneas were analyzed microscopically and tear fluid production was measured by a modified Schirmer test. RESULTS: Corneal lesions were observed as early as the fifth week after birth. The lesions consisted of calcium phosphate and appeared as punctate, crystalline opacities located subeithelially. Lesions were present in 72% (56 of 78) of the MRL/Mp mice, with no significant difference in incidence between MRL/Mp +/+ and MRL/Mp lpr/lpr mice. Corneal calcification was occasionally associated with a self-limiting keratitis and neovascularization. In control mice, corneal opacities were not observed before the animals were 6 months of age. Levels of circulating parathyroid hormone decreased significantly during the first 16 weeks of age in MRL/Mp mice. In addition, MRL/Mp mice of both sexes had a significantly lower tear fluid production as compared to BALB/c mice of the same age. CONCLUSION: Because corneal lesions start to develop in 5-week-old MRL/Mp mice, thereby preceding the clinical signs of systemic autoimmune disease, and may develop in 6-month-old nonautoimmune-prone mice, it is suggested that calcification develops independent of the systemic autoimmune disease and might be restricted to the cornea.

[Fish eye disease]. / Fischaugenkrankheit.

A 67-year-old man complained of impaired vision at night for several months. He was known to have arcus senilis (arcus lipoides corneae) since aged 21 years. For the last 20 years both corneas had become progressively more cloudy. His mother was said to have had similar eye changes. Ophthalmological examination discovered no abnormality other than marked corneal dystrophy with hardly separable arcus senilis. General physical examination was normal. Total cholesterol and triglyceride levels in serum were within normal limits, but serum concentration of high density lipoprotein (HDL) cholesterol (8 mg/dl) was reduced as were, within the high density lipoprotein fraction, the concentrations of triglyceride (4 mg/dl), phospholipids (38 mg/dl), the proportion of cholesterol esters (31%), and the cholesterol-esterification rate (51 nmol/ml . h). The HDL-associated activity of lecithin-cholesterol-acetyltransferase activity was scarcely measurable (0.9 nmol/ml . h). The signs in this case (cloudy cornea, marked decrease in serum HDL cholesterol concentration without premature arteriosclerosis) are typical of fish eye disease.

Erythrocyte abnormalities in a hypoalphalipoproteinemia syndrome resembling fish eye disease.

Erythrocyte membrane (EM) abnormalities in a 16-yr-old boy with hypoalphalipoproteinemia resembling fish eye disease (FED-LS) were investigated. The proband's erythrocytes had markedly decreased osmotic fragility with target cells observed in the peripheral film. Analysis of his EM lipids revealed normal cholesterol and phospholipid content but a marked increase in phosphatidylcholine with concomitant decreases in phosphatidylethanolamine and sphingomyelin. Of the EM enzymes examined, acetylcholinesterase and superoxide dismutase activities were decreased while those of Na+-K+ ATPase, catalase and glutathione reductase were normal. 51Cr erythrocyte survival in the patient was slightly decreased. The observed changes in a number of structural and functional properties of erythrocytes in this disorder are indistinguishable from those previously described in homozygotes for familial lecithin:cholesterol acyltransferase (LCAT) deficiency. Thus, it is possible that in both of these disorders an abnormality of plasma LCAT activity causes, either directly or indirectly, functional and structural changes in the erythrocyte membrane.

Selective reduction of cholesterol in HDL2 fraction by probucol in familial hypercholesterolemia and hyperHDL2 cholesterolemia with abnormal cholesteryl ester transfer.

Long-term treatment with probucol induced marked regression of xanthoma in patients with both homozygous and heterozygous familial hypercholesterolemia despite a substantial accompanying decrease in high-density lipoprotein (HDL) cholesterol. Furthermore, a close correlation was found between the extent of the regression and the reduction of HDL cholesterol, which suggests that the probucol-induced decrease in HDL may not be an atherogenic change, but may reflect a favorable change for lipoprotein metabolism. The present study also evaluated the effects of probucol on HDL metabolism in patients with familial hyperHDL2 cholesterolemia who had extremely high levels of HDL cholesterol ranging from 130 to 280 mg/dl. Premature corneal opacities were present in 2 patients, 1 of whom also had coronary artery disease despite high HDL cholesterol levels. In the 2 cases, the net transfer of cholesteryl ester from HDL to very low density lipoprotein and LDL was impaired, and low hepatic triglyceride lipase activity was observed, but cholesteryl ester transfer protein was not deficient. Administration of probucol to these patients caused a marked reduction of serum cholesterol, which was accounted for exclusively by a reduction in the HDL2 fraction. The size of the HDL2 particles, which had been much larger, decreased to normal, and the net transfer rate of cholesteryl ester was normalized. In the other 3 cases of hyperHDL2 cholesterolemia, the cholesteryl ester transfer activity was completely deficient. Unlike its effect in the first 2 cases, probucol did not cause any change in lipid and apoprotein in the 3 patients with complete deficiency of cholesteryl ester transfer activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Familial LCAT deficiency and fish-eye disease.

Familial LCAT deficiency is due to deficiency of plasma lecithin-cholesterol acyltransferase. The plasma is rich in free cholesterol and lecithin while cholesterol ester and lysolecithin levels are reduced. Analysis of the abnormal lipoproteins has helped our understanding of plasma lipid and lipoprotein metabolism in normals and in patients with liver disease. Proteinuria and anaemia are common and there is marked corneal lipid deposition. Eventually renal function deteriorates and dialysis and/or renal transplantation may be necessary. The human LCAT gene has been sequenced and been shown to be present on chromosomal segment 16q22-the region predicted on the basis of recombination studies as the site of the LCAT deficiency gene. The gene defect has been identified in some cases, but the mechanism remains unclear as the mutations were not in the region presumed to be the enzyme's active site. Only three cases of fish-eye disease have been described; all were elderly and had obvious corneal opacities. They had fasting hypertriglyceridaemia and increased VLDL. IDL and LDL were increased and were triglyceride rich. HDL, reduced by 90%, was mainly HDL3--with a high free and low ester cholesterol. LCAT activity in fish-eye plasma was normal but when measured in an exogenous substrate it was only 10-15% of normal. Fish-eye HDL is a substrate for purified LCAT, but fish-eye LCAT does not esterify free cholesterol of HDL (normal or fish-eye), although it esterifies free cholesterol of VLDL and LDL. It has been suggested that one type of LCAT activity acts on HDL (alpha-LCAT) and another on VLDL and LDL (beta-LCAT)--and that fish-eye disease is due to alpha-LCAT deficiency, and classical familial LCAT deficiency due to lack of both components.

Low A-esterase activity in serum of patients with fish-eye disease.

The activity of HDL-associated paraoxonase in the lipoprotein fraction of serum from two patients with fish-eye disease (FED) was only 11% of the mean value for control subjects. Similarly, concentrations of apolipoproteins A-I and A-II in the serum of FED subjects were only 10% of those in normal subjects. Thus the ratio of enzyme activity to A-I and A-II is virtually the same in these two groups of subjects. This suggests that paraoxonase activity of the lipoprotein fraction is associated with one or both of these apolipoproteins.

In vitro normalization of cholesteryl ester content and particle size of fish eye disease high density lipoproteins.

Isolated high density lipoprotein (HDL) from the two living fish eye disease patients have been incubated in vitro with autologous lipoprotein depleted plasma or with lipoprotein depleted plasma from domestic pig (Sus domesticus), with and without the presence of LCAT inhibitor for 24 hours at 0 and 37 degrees C. The lecithin:cholesterol acyltransferase (LCAT) activity in lipoprotein depleted pig plasma increased the abnormally low cholesteryl ester content of the fish eye disease HDL particles from about 20 to 100% and increased their exceptionally small mean particle size, probably by particle fusion, to a range which is representative of normal HDL3. Both esterification and particle enlargement were totally blocked by the LCAT inhibitor. Incubation of concentrated fish eye disease HDL with autologous lipoprotein depleted plasma for 24 hours at 37 degrees C resulted in a small increase in its cholesteryl ester percentage to 37%, without affecting the apparent HDL particle size. This finding confirms a deficiency of HDL lecithin:cholesterol acyltransferase activity (alpha-LCAT) in fish eye disease. The observed normalization of both HDL cholesteryl ester percentage and particle size by lipoprotein depleted pig plasma which contains virtually no cholesteryl ester transfer activity indicates that the latter is not a requisite for esterification of the free cholesterol of fish eye disease HDL.

Inhibitory effect of normal high density lipoproteins on lecithin:cholesterol acyltransferase activity in fish eye disease plasma.

The lecithin:cholesterol acyltransferase (LCAT) activity of lipoprotein depleted normal and fish eye disease (FED) plasma was assayed in a modified Glomset-Wright incubation system where the enzyme was allowed to act on three different normal lipoprotein substrates consisting of an authentic mixture of very low (VLDL), low (LDL) and high (HDL) density lipoproteins to assay total LCAT activity, HDL to assay alpha-LCAT activity and combined VLDL and LDL to assay beta-LCAT activity, respectively. However, using normal plasma depleted of HDL, leaving its combined VLDL and LDL as enzyme substrate, resulted in a more than twofold increase in the LCAT activity of FED plasma from the two patients compared to the activity obtained with HDL present in the incubation mixture, indicating an inhibitory effect of HDL on the beta-LCAT activity present in FED plasma. This inhibitory effect of normal HDL could also be demonstrated by autoincubation of FED plasma mixed with isolated HDL2 or HDL3. Both these HDL subfractions had a pronounced inhibitory effect on the cholesteryl ester formation in FED plasma. The present study thus clearly demonstrates that normal HDL inhibits the beta-LCAT activity present in FED plasma, esterifying the free cholesterol of combined VLDL and LDL, derived from controls as well as from the two FED patients.

Alpha-lecithin:cholesterol acyltransferase deficiency. Lack of both phospholipase A2 and acyltransferase activities characteristic of high density lipoprotein lecithin:cholesterol acyltransferase in fish eye disease.

The phospholipase A2 and acyltransferase activities characteristic of human plasma lecithin: cholesterol acyltransferase have been evaluated in incubation mixtures of lipoprotein depleted plasma of fish eye disease patients and autologous HDL or homologous normal HDL3. Both enzyme activities were strongly reduced as compared to those of normal controls. These findings further support the claim that fish eye disease plasma has a specific lack of high density lipoprotein lecithin:cholesterol acyltransferase (alpha-LCAT deficiency), although the cholesterol esterification of combined VLDL and LDL in such plasma proceeds at a normal rate.

Different substrate specificities of plasma lecithin: cholesterol acyl transferase in fish eye disease and Tangier disease.

Esterification of plasma free cholesterol is mediated by lecithin:cholesterol acyl transferase (LCAT). The free cholesterol of plasma high density lipoproteins (HDL) is considered to be the preferred substrate for LCAT. It therefore appeared as a paradox that plasma cholesterol esterification, both in vivo and in vitro, is normal in fish eye disease and Tangier disease, two familial conditions with extremely low plasma HDL levels. Fish eye disease plasma, however, was shown to have LCAT activity primarily acting on combined very low (VLDL) and low (LDL) density lipoproteins, denominated beta-LCAT, while it lacked LCAT activity esterifying HDL cholesterol (alpha-LCAT). Here we show that Tangier plasma, in contrast, has both alpha- and beta-LCAT. Thus, in both fish eye and Tangier diseases it is beta-LCAT that explains the apparent normal plasma cholesterol esterification. We also show that Tangier plasma, having alpha-LCAT activity, normalizes the low cholesteryl ester content as well as the abnormally small size of fish eye disease HDL particles during incubation.

Paradoxical esterification of plasma cholesterol in fish eye disease.

The activity of lecithin: cholesterol acyl transferase (LCAT), the enzyme which catalyses the esterification of human plasma cholesterol, has been measured by two independent methods in plasma from the two known living Swedish patients with fish eye disease. The enzyme activity was in both cases about 15% of that of normal plasma. Paradoxically, however, the percentage of plasma cholesterol which was esterified was almost normal in both patients. In addition, a normal spectrum of the fatty acids of the cholesteryl esters was present indicating a normal cholesterol esterification pathway in vivo. Incubation experiments in vitro of plasma from the two patients also yielded normal cholesterol esterification rates when measured by two different methods. These paradoxical results for cholesterol esterification are discussed on the basis of the present biochemical knowledge of fish eye disease and LCAT deficiency.

Evidence for deficiency of high density lipoprotein lecithin: cholesterol acyltransferase activity (alpha-LCAT) in fish eye disease.

In a rare familial condition, fish eye disease, there is a low relative content of cholesteryl esters in the plasma high density lipoproteins (HDL) but a normal content of these lipids in the very low (VLDL) and low (LDL) density lipoproteins. Lecithin: cholesterol acyltransferase (LCAT) is the enzyme which mediates the esterification of free cholesterol in the plasma lipoproteins. In the present investigation, isolated HDL from our two fish eye disease patients were found to be excellent substrates during in vitro incubations with normal LCAT as present in lipoprotein depleted plasma from control subjects. Almost all free cholesterol of these HDL fractions became esterified and concomitantly the abnormally small fish eye disease HDL particles increased to a size in the range of that of normal HDL particles. Lipoprotein depleted plasma from fish eye disease, however, lacked the property of normal plasma to esterify the free cholesterol of HDL isolated from plasma of fish eye disease patients or control subjects. These results have led to the formulation of a new concept implying that two different LCAT activities exist in normal plasma. One of these activities, denoted alpha-LCAT, is specific for HDL (alpha-lipoproteins) and the other, beta-LCAT, is specific for VLDL-LDL (pre beta- and beta-lipoproteins). Fish eye disease according to this notion is classified as an alpha-LCAT deficiency in contrast to the classical LCAT deficiency which probably lacks both alpha- and beta-LCAT activities.

Marked hyper-HDL2-cholesterolemia associated with premature corneal opacity. A case report.

We report here a peculiar case with premature corneal opacity and extremely high levels of HDL cholesterol in serum. The patient is a 54-year-old man who was first noticed to have marked corneal opacities at age 19. His serum HDL cholesterol level was elevated to the level of 135-160 mg/dl, while total serum cholesterol and triglyceride concentrations were 254 mg/dl and 56 mg/dl, respectively. Serum apoprotein A-I and E levels analyzed by single radial immunodiffusion method were elevated in the case. Serum lipoprotein fractions isolated by preparative ultracentrifugation revealed that increased levels of HDL cholesterol were accounted for solely by the HDL2 fraction. HDL2 of the patient contained relatively higher amounts of apoprotein E than normal control HDL2. Elution profiles of lipoproteins in high performance liquid chromatography revealed that HDL2 particles from the patient were larger in size than those from normal controls. These characteristics of HDL are in part similar to those of HDLC which appears in experimental animals after cholesterol feeding. Such abnormalities in HDL2 fractions associated with premature corneal opacity have not been reported so far and appear to constitute a new disease entity.