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Biomedical subjects

A Pinckers

Publications and source records attributed to A Pinckers.

At least 19 recordsLinked to original sources
PubMed2000

The luminance fall in anomaloscope examination: clinical examples.

PURPOSE: The evaluation of the anomaloscope slope quotient in patients with acquired colour vision deficiency. METHODS: Two patients with Stargardt's disease in combination with protanomaly and deuteranomaly, respectively, were selected and also 3 patients with a presumed dominant optic atrophy of the protan type. The anomaloscope examination was performed according to the Linksz procedure. The luminance fall was calculated as the slope quotient SQ:Y units luminance fall per X units width of the matching range. RESULTS: The SQ of the 2 Stargardt patients was steeper than the SQ of congenital colour vision defectives, especially at the red end of the anomaloscope green-red mixture scale, indicating pathologic scotopization superimposed on the congenital deficiency. In optic atrophy of the protan type the SQ was flatter than in congenital deficiency, indicating that this deficiency has nothing to do with congenital protan deficiency. CONCLUSION: Calculation of the slope quotient SQ is helpful for the diagnosis of acquired colour vision deficiency, especially when the subject also has a congenital colour vision deficiency or is supposed to have such a deficiency.

Adult↗
PubMed2000

The complete form of X-linked congenital stationary night blindness is caused by mutations in a gene encoding a leucine-rich repeat protein.

X-linked congenital stationary night blindness (XLCSNB) is characterized by impaired scotopic vision with associated ocular symptoms such as myopia, hyperopia, nystagmus and reduced visual acuity. Genetic mapping in families with XLCSNB revealed two different loci on the proximal short arm of the X chromosome. These two genetic subtypes can be distinguished on the basis of electroretinogram (ERG) responses and psychophysical testing as a complete (CSNB1) and an incomplete (CSNB2) form. The CSNB1 locus has been mapped to a 5-cM linkage interval in Xp11.4 (refs 2,5-7). Here we construct and analyse a contig between the markers DXS993 and DXS228, leading to the identification of a new gene mutated in CSNB1 patients. It is partially deleted in 3 families and mutation analysis in a further 21 families detected another 13 different mutations. This gene, designated NYX, encodes a protein of 481 amino acids (nyctalopin) and is expressed at low levels in tissues including retina, brain, testis and muscle. The predicted polypeptide is a glycosylphosphatidylinositol (GPI)-anchored extracellular protein with 11 typical and 2 cysteine-rich, leucine-rich repeats (LRRs). This motif is important for protein-protein interactions and members of the LRR superfamily are involved in cell adhesion and axon guidance. Future functional analysis of nyctalopin might therefore give insight into the fine-regulation of cell-cell contacts in the retina.

Amino Acid Motifs↗
PubMed1999

Craniosynostosis associated with ectopia lentis in monozygotic twin sisters.

Ectopia lentis has rarely been reported to occur in association with craniosynostosis, and this was found only in sporadic cases. We report on twin sisters who underwent surgery for craniosynostosis and later on, at age 3 years, were found to have bilateral ectopia lentis. Molecular studies yielded a probability of monozygosity of more than 0.98. Inheritance of the syndrome may be autosomal dominant, possibly due to a new mutation, autosomal recessive, or X-linked with male lethality.

Abnormalities, Multiple↗
PubMed1999

Anomaloscope examination: scotopization (the luminance fall).

PURPOSE: The evaluation of a criterion for the detection of pathologic scotopization in routine anomaloscope examination. METHODS: Fifty congenital protan subjects, 50 congenital deutan subjects, 30 autosomal recessive congenital achromats, and 25 (44 eyes) acquired type I red-green defective subjects were selected. The anomaloscope examination was according to the Linksz procedure. The luminance fall was calculated as the slope quotient SQ: Y units luminance fall per X units width of the matching range. RESULTS: The mean SQ was -0.01 for congenital deutan subjects, -0.40 for congenital protan subjects and -1.30 for congenital achromats. There was no overlap between the three groups. Pathologic scotopization was found in 98% of the eyes presenting with an acquired type I colour vision defect. CONCLUSION: Calculation of the slope quotient SQ is helpful for the detection of pathologic scotopization in acquired colour vision deficiency.

Color Vision Defects↗
PubMed1998

Congenital corneal anesthesia in children with the VACTERL association.

PURPOSE: To describe ocular manifestations in patients with the VACTERL (vertebral, anal, cardiovascular, tracheoesophageal, renal, and limb defects) association. METHOD: We reviewed the medical records of patients with the VACTERL association who had undergone treatment for amblyopia at the orthoptic department. RESULTS: A striking similarity was found in three unrelated children, who, in addition to clinical manifestations of VACTERL association, showed total corneal anesthesia of one or both eyes that had resulted in recurrent corneal erosions, keratitis, and permanent corneal opacities. Other ocular manifestations included nonparalytic strabismus, anisometropia, and amblyopia. CONCLUSION: Congenital corneal anesthesia may be part of the VACTERL association.

Abnormalities, Multiple↗
PubMed1998

Mutation analysis of patients with Hermansky-Pudlak syndrome: a frameshift hot spot in the HPS gene and apparent locus heterogeneity.

Hermansky-Pudlak syndrome (HPS) is a rare, autosomal recessive disorder in which oculocutaneous albinism, bleeding, and lysosomal ceroid storage result from defects of multiple cytoplasmic organelles-melanosomes, platelet-dense granules, and lysosomes. As reported elsewhere, we mapped the human HPS gene to chromosome segment 10q23, positionally cloned the gene, and identified three pathologic mutations of the gene, in patients from Puerto Rico, Japan, and Europe. Here, we describe mutation analysis of 44 unrelated Puerto Rican and 24 unrelated non-Puerto Rican HPS patients. A 16-bp frameshift duplication, the result of an apparent founder effect, is nearly ubiquitous among Puerto Rican patients. A frameshift at codon 322 may be the most frequent HPS mutation in Europeans. We also describe six novel HPS mutations: a 5' splice-junction mutation of IVS5, three frameshifts, a nonsense mutation, and a one-codon in-frame deletion. These mutations define an apparent frameshift hot spot at codons 321-322. Overall, however, we detected mutations in the HPS gene in only about half of non-Puerto Rican patients, and we present evidence that suggests locus heterogeneity for HPS.

Albinism, Oculocutaneous↗
PubMed1996

Autosomal dominant central areolar choroidal dystrophy caused by a mutation in codon 142 in the peripherin/RDS gene.

PURPOSE: Because several macular dystrophies are caused by mutations in the peripherin/RDS gene, we examined autosomal dominant and sporadic cases of central areolar choroidal dystrophy for mutations in the peripherin/RDS gene. METHODS: DNA sequence analysis of the peripherin/RDS gene was performed in four sporadic cases and in ten affected and nine unaffected individuals from seven families with autosomal dominant central areolar choroidal dystrophy. RESULTS: An Arg-142-Trp mutation in the peripherin/RDS gene was found in ten affected family members in seven families. Among these, a 69-year-old man with the Arg-142-Trp mutation, who was unaffected six years before blood sample analysis, showed a parafoveal area of chorioretinal atrophy. The 65-year-old sister of this family had the Arg-142-Trp mutation with no macular abnormalities, but she might still develop central areolar choroidal dystrophy at an older age. No mutation was found in the four sporadic cases. CONCLUSION: Autosomal dominant central areolar choroidal dystrophy, studied in seven families, is caused by an Arg-142-Trp mutation in the peripherin/RDS gene.

Adult↗
PubMed1996

The EOG in Best's disease and dominant cystoid macular dystrophy (DCMD).

The electro-oculogram (EOG) was studied in 156 normal patients, 103 patients with Best's disease, and 52 patients with dominant cystoid macular dystrophy (DCMD). Statistical analysis was performed by comparing the distribution of Lp/Dt ratios of the groups. Strength of association between Lp/Dt ratio and age was studied with correlation and regression analysis. In normal patients and in those with Best's disease, there was no significant correlation between age and Lp/Dt ratio. Obviously, the gene defect in Best's disease causes an altered light-sensitive slow oscillation that remains stable throughout life. In DCMD patients, there was a significant negative correlation between age and Lp/Dt ratio for the total sample and for the female subgroup. Likely, the gene defect in DCMD interferes with capillary permeability, that becomes susceptible to changes of the female hormones.

Adolescent↗
PubMed1995

Clinical findings in obligate carriers of type I Usher syndrome.

Seventeen obligate carriers from nine families with autosomal recessive Usher syndrome type I underwent otological, audiological, vestibular, and ophthalmological examination in order to identify possible manifestations of heterozygosity. Linkage studies were performed and six families showed linkage to chromosome region 11q13.5 while 3 families have so far failed to show linkage to the candidate regions. Eight obligate carriers had an abnormal pure-tone audiogram. Two different audiometric patterns could be distinguished when hearing loss was corrected for age and sex. Four carriers (24%) had significant sensorineural hearing loss (SNHL) which increased at higher frequencies. The other 13 carriers had SNHL of about 10 dB at 0.25 and 0.5 kHz, but less at higher frequencies. Vestibular findings were generally normal. Electro-oculography demonstrated a significant lower mean light peak/dark trough ratio in Usher type I carriers compared to normal control individuals. The methods used in this study were found not to be specific enough to clinically identify carriers of Usher type I syndrome. Nevertheless it is remarkable that a number of obligate carriers showed significant audiological and ophthalmological abnormalities.

Adult↗
PubMed1995

Linkage analysis in a Dutch family with X-linked recessive congenital stationary night blindness (XL-CSNB).

Linkage analysis has been performed in a large Dutch pedigree with X-linked recessive congenital stationary night blindness (CSNB) by utilizing 16 DNA markers from the proximal short arm of the human X chromosome (Xp21.1-11.2). Thirteen polymorphic markers are at least partially informative and have enabled pairwise and multipoint linkage analysis. For three loci, i.e. DXS228, the monoamine oxidase B gene and the Norrie disease gene (NDG), multipoint linkage studies have yielded maximum lod scores of > 3.0 at a recombination fraction of zero. Analysis of recombination events has enabled us to rule out the possibility that the underlying defect in this family is allelic to RP3; the gene defect could also be excluded from the proximal part of the region known to carry RP2. Linkage data are consistent with a possible involvement of the NDG but mutations in the open reading frame of this gene have not been found.

Chromosome Mapping↗
PubMed1995

Ocular and systemic manifestations of cerebrotendinous xanthomatosis.

PURPOSE: Cerebrotendinous xanthomatosis is a storage disease that usually leads to severe mental and neurologic deterioration before the diagnosis and start of treatment are established. We identified major ocular and systemic characteristics that may enable a diagnosis to be made earlier. METHODS: Ten patients (group 1) of the University Hospital Nijmegen, with a diagnosis of cerebrotendinous xanthomatosis, were re-examined for detailed ocular and major clinical manifestations. Meanwhile, we looked for similar but undiagnosed cases in patients (group 2) who visited the Institute of Ophthalmology during a 12-month period. RESULTS: A diagnosis of cerebrotendinous xanthomatosis had been made in the patients of group 1 at an average age of 40 years (range, 33 to 48 years). Subsequently, six new cases (group 2) were diagnosed in patients 7 to 37 years old (average age, 18 years). Bilateral cataract was the major ocular manifestation in all 16 patients. Small irregular corticonuclear opacities, anterior polar cataracts, and dense posterior subcapsular cataracts were diagnosed at various ages (mean, 18 years; range, 4 to 40 years). Four patients showed clinical signs of optic neuropathy, whereas retinal function was normal in all patients. Other major clinical signs included a history of chronic diarrhea (since childhood), mental deterioration (mean age, 23 years), neurologic deterioration (mean age, 31 years), and tendon xanthomas (mean age, 37 years). CONCLUSIONS: Appropriate biochemical investigations for cerebrotendinous xanthomatosis should be performed in patients with unexplained juvenile or early-onset adult cataracts, especially if these cataracts are associated with chronic diarrhea since infancy, mental retardation or deterioration, neurologic dysfunction, or xanthomas.

Adolescent↗
PubMed1995

A spider hits the eye.

To determine the necessary medical care and permanent ocular damage of a particular type of preventable ocular trauma, an observational study of 22 patients referred to the University Hospital Nijmegen (1983-1993) with eye injuries caused by the accidental release of tightened elastic straps of the so-called "spider' design was performed. Although the traumatized eyes of the 22 patients could be saved from blindness by extensive medical and surgical treatment in the majority of cases, 13 patients (59%) had residual permanent visual impairment (visual acuity < or =6/10, or aphakia) at the end of the follow-up period. Three of them had lost the perception of light in the involved eye; one painful blind eye had to be removed. It is concluded that elastic straps with free-end metal hooks should not be used to secure luggage because of the potential risk of irreversible damage to the eye.

Adolescent↗
PubMed1995

Ectopia lentis et pupillae syndrome in three generations.

In nine members from three generations and in a distant relative, at least three significant characteristics of the ectopia lentis et pupillae syndrome were established including ectopia lentis, ectopia pupillae, persistent pupillary membrane, iris transillumination, and poor pupillary dilatation. All patients developed bilateral cataract before the age of 40 years, and two patients presented with intermittent acute intraocular hypertensive crises. Not only the high number of patients in one family, but also the occurrence in three generations is very exceptional for the ectopia lentis et pupillae syndrome. Although the syndrome is said to be inherited in an autosomal recessive mode, in this family, a mother to son and a mother to daughter transmission were present. Pedigree analysis yielded arguments in favour of an autosomal dominant inheritance with reduced penetrance. A biochemical correlation was not identified.

Adult↗
PubMed1994

Pathologic scotopization: a shortened Nagel-II anomaloscopic micro-screw method.

The Nagel-II micro-screw method uses eleven colour equations between 620 and 560 nm. The luminance settings are given and are based on the data of colour normal individuals. In the shortened version, intended to detect pathologic scotopization, it is ascertained at which position of the micro-screw the patient's colour adjustments drop beneath the level of 60 scale Units. A total of 64 patients was examined. 29 congenital colour defectives and 35 acquired colour defectives. With the shortened micro-screw method the patients can be divided into four groups: (1) a group without pathologic scotopization, which includes congenital protan defectives: (2) a group in which pathologic scotopization starts; (3) a group with evident pathologic scotopization, due to Stargardt's disease and other cone dystrophies; and (4) a group with complete pathologic scotopization, which includes the congenital achromats and the end-stages of the cone dystrophies.

Color Perception Tests↗
PubMed1994

Localization of the gene for dominant cystoid macular dystrophy on chromosome 7p.

In a family with autosomal dominant cystoid macular dystrophy (DCMD) linkage was detected with the dinucleotide marker D7S435 on the short arm of chromosome 7. With markers flanking D7S435, the DCMD locus could be assigned to the interval D7S493-D7S526 at 7p15-p21, which spans approximately 20 cM. Three-point linkage yielded a maximal lod score of 9.46 and location score of 43.5 and suggested that DCMD is 5,5 cM proximal to D7S493. Recently, a retinitis pigmentosa (RP7) locus has been mapped in roughly the same area of chromosome 7. Genetic data of both studies described below, allow a region of overlap between the location of the DCMD and the RP7 gene between D7S435 and D7S526. Both genes being one and the same will further substantiate the close relationship between macular degeneration and retinitis pigmentosa.

Age of Onset↗
PubMed1994

The electrooculogram in heterozygote carriers of Usher syndrome, retinitis pigmentosa, neuronal ceroid lipofuscinosis, senior syndrome and choroideremia.

Electrooculographic studies were performed in 77 carriers of tapetoretinal dystrophies: Usher syndrome (20), retinitis pigmentosa (32), neuronal ceroid lipofuscinosis (6), Senior syndrome (2), and choroideremia (17). The carriers were matched for sex and age with normal controls. In carriers of Usher syndrome the EOG Lp/Dt ratio was significantly lowered with 30% of the recordings having a subnormal value. There was a trend in carriers of retinitis pigmentosa to a subnormal EOG. In contrast to previous studies there was no decrease in the EOG Lp/Dt ratio in carriers of neuronal ceroid lipofuscinosis. Two carriers of Senior's syndrome had a normal EOG. Carriers of choroideremia did not differ significantly from normal controls; however, the Lp/Dt ratio decreased with increasing age. An abnormal EOG may be indicative of the carrier state in relatives of patients with tapetoretinal dystrophies.

Adult↗
PubMed1993

Colour vision in retinitis pigmentosa. Influence of cystoid macular edema.

In retinitis pigmentosa patients the effect of cystoid macular edema on colour vision was studied. The occurrence of cystoid macular edema decreases with increasing colour vision defect. The mutual proportion of the main types of colour vision defects remains stable until visual acuity has dropped to 0.5; at lower VA levels the number of red-green defects increases. Neither the finding of a blue-yellow colour vision defect in FM100 Hue testing nor the appearance of anomaloscopic pseudoprotanomaly is influenced by cystoid macular edema. The authors conclude that cystoid macular edema in retinitis pigmentosa patients mainly affects visual acuity and not colour vision. They also noted a familial occurrence of cystoid macular edema.

Color Perception↗