Time-resolved fluorometry in the diagnosis of Leber hereditary optic neuroretinopathy

We have applied time-resolved fluorometry (TRF) to construct a DNA hybridization assay for the diagnosis of Leber hereditary optic neuroretinopathy (LHON). A rapid and reliable detection of the most prevalent mitochondrial DNA (mtDNA) point mutation associated with LHON is demonstrated. In addition, the TRF-method can be used in the quantification of heteroplasmy, a phenomenon commonly present in mtDNA mutations. The assay includes PCR amplification of a fragment encompassing the mutation site followed by hybridization reactions with allele-specific europium (Eu)-labelled oligonucleotide probes. A time-resolved fluorometer is used to measure the bound label. The TRF assay was successfully used to demonstrate the ND4/11778 mutation in patient samples. For quantification of heteroplasmy, synthetic target oligonucleotide mixtures with known ratios of wild-type and mutated sequences were used as standards to control the hybridization step. The assay allowed the detection of heteroplasmy ranging from 5 to 95%. This was also shown in a family with several heteroplasmic members.

Quantification of point mutations associated with Leber hereditary optic neuroretinopathy by solid-phase minisequencing

About two-thirds of patients with Leber hereditary optic neuroretinopathy (LHON) harbor mutations in mitochondrial DNA at positions 11778 (ND4) or 3460 (ND1). Thus, the clinical diagnosis of LHON can often be confirmed with mutation analysis. Detection of pathogenic mutations and quantification of heteroplasmy has mainly relied on PCR and restriction site analysis and densitometric scanning. We applied the recently developed solid-phase minisequencing method, based on primer-guided nucleotide incorporation, to the simultaneous detection and quantitation of the ND4/11778 and ND1/3460 mutations. The method was highly sensitive, heteroplasmy as low as 1.5% being easily detected. Rapid, reproducible, and accurate results prove solid-phase minisequencing to be the method of choice for quantitative analysis of LHON mutations.

The spectrum of mitochondrial DNA mutations in families with Leber hereditary optic neuroretinopathy

The mitochondrial complex I genes were sequenced in seven Leber hereditary optic neuroretinopathy (LHON) families without the ND4/11,778 and ND1/3460 mutations. Four replacement mutations restricted only to LHON families were found, one in the ND1 gene at nt 4025, and three in the ND5 gene at nt 12,811, 13,637, and 13,967. The mutations did not change evolutionarily conserved amino acids suggesting that they are not primary LHON mutations in these families. They may be considered as secondary LHON mutations serving as exacerbating factors in an appropriate genetic background. A complex III mutation, cyt b/15,257, has been suggested to be one of the primary mutations causing LHON. Its presence was determined for 23 Finnish LHON families, and it was detected in two families harboring the ND4/11,778 mutation. Similarly, complex IV mutation COI/7444 was screened in Finnish LHON families, and it was found in one family carrying the ND1/3460 mutation.

Electron transfer properties of NADH:ubiquinone reductase in the ND1/3460 and the ND4/11778 mutations of the Leber hereditary optic neuroretinopathy (LHON)

We report the electron transfer properties of the NADH:ubiquinone oxidoreductase complex of the respiratory chain (Complex I) in mitochondria of cells derived from LHON patients with two different mutations in mitochondrial DNA (mtDNA). The mutations occur in the mtDNA genes coding for the ND1 and ND4 subunits of Complex I. The ND1/3460 mutation exhibits 80% reduction in rotenone-sensitive and ubiquinone-dependent electron transfer activity, whereas the proximal NADH dehydrogenase activity of the Complex is unaffected. This is in accordance with the proposal that the ND1 subunit interacts with rotenone and ubiquinone. In contrast, the ND4/11778 mutation had no effect on electron transfer activity of the Complex in inner mitochondrial membrane preparations; also Km for NADH and NADH dehydrogenase activity were unaffected. However, in isolated mitochondria with the ND4 mutation, the rate of oxidation of NAD-linked substrates, but not of succinate, was significantly decreased. This suggests that the ND4 subunit might be involved in specific aggregation of NADH-dependent dehydrogenases and Complex I, which may result in fast ('solid state') electron transfer from the former to the latter.

DXS26 (HU16) is located in Xq21.1

We have localized a single-copy DNA probe, HU16 (locus DXS26), to Xq21.1. The probe was isolated from a human-mouse hybrid X;13 library and mapped with human-mouse hybrids containing different portions of the human X chromosome and DNA from male patients with different X-chromosomal deletions. The following order of loci is proposed: Xcen-(DXS72,DXS169)-(DXS232,DSX26)-DXS1 21-DXS233-DXS165-TCD-DXS95-DXYS1-Xqter. HU16 will be useful in the study of the putative genes that reside in Xq21 and whose defects lead to deafness and mental retardation.

Familial olivopontocerebellar atrophy with macular degeneration: a separate entity among the olivopontocerebellar atrophies

A family with hereditary, neuropathologically confirmed olivopontocerebellar atrophy (OPCA) associated with macular degeneration is described. The mode of inheritance was autosomal dominant. The first symptom was insidious, progressive visual loss caused by macular degeneration. Another early sign was slow saccades. Some years after the visual symptoms, gradually progressing cerebellar dysfunction and pyramidal signs developed. Computed tomography of the brain indicated cerebellar and pontine atrophy. Finally the patients were blind, due to a severe chorioretinal atrophy, and disabled because af motor dysfunction. The present study, together with a review of other reported families with OPCA associated with macular degeneration, suggests that this disorder is a specific and clinically recognizable subtype of OPCA.

Fundus findings in Leber's hereditary optic neuroretinopathy

The acute stage of Leber's hereditary optic neuritis is characterized by dilated disc arterioles accompanied, in some cases, by superficial peripapillary hemorrhages. Decreased vision caused by centrocecal scotoma is accompanied by slow and deficient capillary filling in the papillomacular bundle and arteriovenous shunting in the upper and lower vascular arcades. These and other vascular changes disappear in the more advanced stages (optic atrophy) of the disease.

Fundus findings in Leber's hereditary optic neuroretinopathy. III. Fluorescein angiographic studies

Fluorescein angiography was performed in nine members of families with Leber's disease. Serial studies were obtained in four men observed from asymptomatic to atrophic stages. Peripapillary microangiopathy was observed in six of nine asymptomatic eyes. Arteriovenous shunting occurred in the telangiectatic vascular bed. These changes remained stable in some eyes and progressed in others. In the acute stage, arteries and telangiectatic vessels were maximally dilated and flow was rapid. Angiography showed florid shunting in lower and upper vascular arcades and reduced filling of papillomacular capillaries. Vessels of the shunting vascular bed gradually narrowed irregularly. In the atrophic stage, disc vascularity diminished and arteriovenous circulation time increased markedly. Arterioles narrowed and peripapillary microangiopathy disappeared. These findings support our contention that Leber's disease is a hereditary vascular neuroretinopathy.

Monoclonal IgG immunoglobulinemia with subsequent myeloma in psoriatic arthritis

A 42-year-old man had suffered from skin psoriasis for 27 years, psoriasis arthritis for 6 years and corneal crystalline deposits for 1 year, when an IgG-kappa monoclonal immunoglobulin was detected in his serum electrophoretic pattern. All the diagnostic studies for multiple myeloma were negative. However, 16 months later he developed this disease.

Interferon-alpha and interferon-gamma production capacity of idiopathic isolated optic neuritis patients

Interferon-alpha and interferon-gamma production by idiopathic isolated optic neuritis (ON) patients was studied. The production capacity was compared with that in two control groups: patients with iritis and healthy control subjects. A sensitive and reliable interferon bioassay was applied for interferon level measurements. Statistically significant differences were not found between patients and control groups in either interferon-alpha production or interferon-gamma production.

Ophthalmoscopic findings in Leber's hereditary optic neuropathy. II. The fundus findings in the affected family members

Eighteen men and four women had Leber's disease. Fundus photographs obtained in three cases showed the following: Peripapillary microangiopathy, present from the beginning, slowly increased during the presymptomatic stage. At the end of the presymptomatic stage, the nerve fiber layer became swollen. During the acute stage, retinal vessels on and around the disc were dilated, tortuous, and telangiectatic. Nerve fiber layer hemorrhages occurred in two eyes. As atrophy appeared first in the papillomacular bundle and then in the remaining retina, the vascular bed involuted, leaving a capillary-poor retina with attenuated arterioles and a pale optic disc. The final degree of atrophy varied. Fifteen of the affected persons were blind with severe optic atrophy, but in seven optic atrophy was only partial, causing less visual handicap. Our results suggest that Leber's disease is primarily an intraocular, not a retrobulbar, optic neuropathy. It should be redesignated as Leber's hereditary neuroretinopathy.

Ophthalmoscopic findings in Leber's hereditary optic neuropathy. I. Fundus findings in asymptomatic family members

A neuro-ophthalmological examination was performed on 47 asymptomatic offspring in the female line and 13 offspring in the male line in families with Leber's hereditary optic neuropathy. Fourteen (61%) of the 23 asymptomatic males and nine (38%) of the 24 asymptomatic females in the female line had telangiectatic microangiopathy of the peripapillary arterioles and capillaries. Increased tortuosity of capillaries, medium-sized arterioles, and venules were also seen in the fundi of several asymptomatic family members. The 13 offsprings in the male line did not have microangiopathy. Nerve fiber abnormalities were not seen in asymptomatic persons. The photographically verified findings are described, classified, and discussed. It is suspected that Leber's disease is primarily a microvascular disorder. The vascular abnormalities detected in the asymptomatic family members probably indicate increased risk of Leber's disease developing. During the prospective follow-up of three years, three asymptomatic boys with microangiopathy have experienced Leber's disease.

Do visual evoked potentials give relevant information to the neuro-ophthalmological examination in optic nerve lesions?

The visual evoked potentials (VEPs) and neuro-ophthalmological examinations of 134 patients were compared. The VEPs were abnormal in 95% of the eyes with optic neuritis. Defective color vision was found in 99%, visual field defects in 88%, decreased vision in 66% and an afferent pupillary defect in 55%. 29 patients with optic neuritis were followed up with repeated tests. VEPs and color vision recovered more slowly than visual acuity and visual field. Abnormal VEPs were observed in 68% of 50 MS patients. An analysis of symptomatic and asymptomatic eyes showed that testing of color vision, visual field and red-free ophthalmoscopy were equally as useful diagnostic tools as VEPs. 4 (8%) of the MS patients had abnormal VEPs despite a normal neuro-ophthalmological examination; 94% of MS patients with symptoms and 47% of MS patients without visual symptoms had abnormal VEPs. VEPs were pathological in 59% of 24 patients with traumatic or compressive optic nerve diseases or optic atrophies of unknown etiology. The neuro-ophthalmological examination was more sensitive than VEPs in the diagnosis of these disorders. A neuro-ophthalmological examination is in most cases sufficient to diagnose optic nerve lesions. VEPs are of diagnostic aid especially in mild optic nerve lesions.

Prognosis of optic neuritis with special reference to cerebrospinal fluid immunoglobulins and measles virus antibodies

Forty-eight patients with optic neuritis (ON), first seen in 1970 to 1973, were neurologically and neuroophthalmologically reexamined after 7 to 10 years. Twenty-seven patients (56%) had probable MS, and 9 (19%) had possible MS. During the attack of ON, the cerebrospinal fluid (CSF) samples and serum/CSF measles antibody ratios were studied. Twenty patients had increased relative immunoglobulin G (IgG) (% of total protein) in their CSF; 19 of these had probable or possible MS. However, 17 of 28 patients with a normal relative IgG value had also developed MS. CSF electrophoresis was abnormal in 20 patients with ON; reexamination showed that 19 had probable or possible MS. Sixteen of 27 patients with normal electrophoresis had also developed MS. Serum/CSF measles antibody ratio had decreased in 19 patients; 13 of these had probable MS and 3 had possible MS. Of 29 patients with a normal measles antibody ratio, 14 had probable MS and 6 had possible MS. The conclusion is that examination of the CSF in ON gives valuable prognostic information because increased relative IgG, abnormal electrophoresis, or a decreased measles antibody ratio implies a high risk of developing MS. A normal CSF does not, however, rule out the possibility of dissemination.

Computerized tomography of the orbits. A report of 196 patients

The value of orbital CCT scans was studied by grouping the CCT scans of 196 patients into clinical diagnostic categories. In 83% of patients with suspected Graves' ophthalmopathy, CCT confirmed the diagnosis. The CCT scan differentiated patients with Graves' disease from those with orbital pseudotumour or malignancies. The CCT scan was positive in 92% or patients with proven orbital malignancies. In 73% of patients with proptosis of unknown aetiology, and in 56% of patients with ocular motility problems, the CCT scan led to the diagnosis. The CCT scan ruled out orbital mass lesions in cases of optic neuritis, optic atrophy or vascular malformations. The greatest value of the CCT scan was in the localization and determination of the size and shape of various orbital lesions and in the accurate follow-up of those lesions utilizing serial scans.

The early phase in Leber hereditary optic atrophy

Clinical, ophthalmoscopic, perimetric, and color vision tests and visual evoked responses were recorded in symptomatic and asymptomatic eyes in five members of a family with Leber hereditary optic atrophy. The presymptomatic eyes showed abnormalities in the retinal nerve fiber layer. Optic nerve dysfunction was found before central vision failed. The appearance of degenerating retinal nerve fibers, particularly in the papillomacular bundle, was documented photographically in the weeks after the onset of visual symptoms. Treatment with prednisone and hydroxocobalamin did not reverse or halt serious impairment of vision.

Parotid carcinoma and posterior fossa schwannoma following irradiation. Report of a patient treated in infancy for benign ear disease

A 23-year-old man had received irradiation for a benign ear problem at the age of 1 year. Twenty year later, a malignant left parotid carcinoma and a right jugular foramen schwannoma developed. Earlier reports in the literature suggest that radiation can induce tumors in the head and neck. The localization of both tumors and the histological features of the parotid tumor suggest that they were radiation-induced.