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Norrie disease (ND), atrophia bulborum hereditaria, is caused by a gene defect on the proximal short arm of the X-chromosome. As shown by us and others, microdeletions spanning the DXS7 locus are not uncommon in this disorder, and there is recent evidence that, at least in some of the Norrie deletion patients, the monoamine oxidase (MAO) A and B genes are deleted as well. Molecular hybridization experiments with 19 cloned DNA fragments have enabled us to construct a preliminary long-range restriction map around DXS77, DXS7, MAO-A and MAO-B, and to localize the distal end point of an ND deletion between DXS77 and DXS7.

The authors present 11 patients with Peters' anomaly, short stature, brachymorphy, mental retardation, abnormal ears and cheilo(gnatho)palatoschisis. The condition can be relatively mild, but also even lethal in the fetal period.

Linkage analysis was carried out in three large multigenerational kindreds with X-linked retinitis pigmentosa using DNA markers on Xp. About 10% recombination has been found between the retinitis pigmentosa locus (RP2) and the marker locus DXS7, assigned to band Xp11.3, which was reported earlier to be closely linked to RP2 in several independent families. In the kindreds described in this paper, however, RP2 shows close linkage and no recombination with the marker loci OTC and DXS148, both assigned to Xp21, indicating that, contrary to previous linkage studies, there is evidence of an RP locus distal to DXS7. This suggests that X-linked retinitis pigmentosa is genetically heterogeneous, i.e., caused by mutations at different loci.

A 15-year-old male patient with the typical ocular symptoms of Norrie disease is described. Additionally, he presents severe mental retardation, growth disturbances, hypogonadism, and increased susceptibility to infections. This complex syndrome is apparently segregating through three generations: four other male relatives of the patient were blind from birth and died from recurrent infections between the ages of three to 15 months. The DNA sequence of the DXS7 locus (L1.28 probe), known to be closely linked to the Norrie gene, was not found in the patient's DNA. This result suggests that the more complex clinical picture seen is the result of a deletion of the X chromosome spanning DXS7, the Norrie gene, and several neighbouring loci. A detailed clinical description of the patient is given and compared to that of similar cases.

Two mentally and physically retarded girls, one with an interstitial deletion 7 (pter leads to q21::q32 leads to qter), and the other with an interstitial deletion 7 (pter leads to q11::q22 leads to qter), are described. Their clinical features are compared with those of 11 earlier reported cases with a deletion 7q. The Hageman factor, the locus of which is assigned to the distal part of 7q, was in both cases within normal limits. The data available do not justify the delineation of a specific clinical syndrome.

A hereditary malformation of the metatarsophalangeal joints, called here "tear drop" deformity, and a cut off appearance of the distal phalanges of the toes is described in a family with double translocation t (7; 12), t (2; 6) heterozygosity. A bracydactyly E was also found. These disorders seemed unrelated to the chromosomal aberration.

In a large pedigree with autosomal dominant aniridia, we found close linkage between the aniridia locus AN2 and the markers catalase (CAT) (zeta = 7.27 at theta = 0.00) and D11S151 (zeta = 3.86 at theta = 0.10) flanking the AN2 locus on 11p13. Positive lod scores were also obtained for the 11p13----11p14 markers D11S16 and FSHB with the linkage group CAT/AN2/D11S151. We conclude that the autosomal dominant aniridia in this family is due to a mutation at the AN2 locus on 11p13. We have excluded linkage (zeta less than -2 at theta less than 0.18) between the aniridia and the chromosome 2p25 marker D2S1 (linked to ACP1).

A severely mentally retarded girl is presented, with symptoms as described by Pitt, Rogers, and Danks (pre- and postnatal growth retardation, and unusual facies). Additional manifestations are glaucoma, pre-auricular pits, and an atrial septal defect.

Peroxisomes play an essential role in human cellular metabolism. Peroxisomal disorders, a group of genetic diseases caused by peroxisomal dysfunction, can be classified in three groups namely a group of disorders with a general peroxisomal dysfunction (Zellweger syndrome; infantile type of Refsum's disease; neonatal adrenoleukodystrophy, hyperpipecolic acidemia), a group with an impairment of some, but not all peroxisomal functions (rhizomelic chondrodysplasia punctata) and a group with impairment of only a single peroxisomal function (acatalasemia, X-linked adrenoleukodystrophy/adrenomyeloneuropathy; adult type of Refsum's disease; peroxisomal thiolase deficiency; peroxisomal acyl-CoA oxidase deficiency; hyperoxaluria type I). In this paper we report the typical findings in ophthalmological examinations of patients suspected of Zellweger syndrome contributing to the clinical diagnosis of this disorder. In biochemical studies using a rapid gaschromatographic detection method for plasmalogens we confirmed that plasmalogens are severely deficient in all tissues of Zellweger patients studied. Moreover, using a recently developed radiochemical method, de novo plasmalogen biosynthesis was found to be impaired in fibroblasts from patients with Zellweger syndrome, infantile Refsum's disease, neonatal adrenoleukodystrophy or rhizomelic chondrodysplasia punctata, this in contrast to X-linked chondrodysplasia in which a normal plasmalogen biosynthesis was found. From the literature it is known that peroxisomal beta-oxidation with both long-chain (C16:0) and very long-chain (C24:0; C26:0) fatty acids is deficient in Zellweger syndrome, infantile Refsum's disease and neonatal adrenoleukodystrophy. In contrast, in X-linked adrenoleukodystrophy only the peroxisomal beta-oxidation of the very long chain fatty acids is impaired. As a result very long-chain fatty acids accumulate in tissues, plasma, fibroblasts and amniotic fluid cells from patients with Zellweger syndrome, infantile Refsum's disease, neonatal and X-linked adrenoleukodystrophy, but not in rhizomelic chondrodysplasia punctata or X-linked chondrodysplasia. Finally we confirmed that the peroxisomal enzyme alanine glyoxylate aminotransferase is severely deficient in liver from a patient that died because of the neonatal type of hyperoxaluria type I, but not in liver from Zellweger patients.

Human fibroblasts derived from four individuals with various deletions in the short arm of one chromosome 11 were susceptible to morphological transformation by early region BK virus DNA, whereas diploid human fibroblasts were not. This difference in susceptibility to transformation by early region BK virus DNA might be explained by a putative 'transformation suppressor' locus situated within the deleted region on the short arm of chromosome 11.

A mild variant of Zellweger (cerebro-hepato-renal) syndrome was diagnosed in male and female siblings aged 7 and 2 years. They had mild facial dysmorphia, moderate psychomotor retardation, tapetoretinal degeneration, sensorineural deafness and hepatomegaly. Ultrastructural examination of a liver biopsy in the younger patient revealed the absence of recognizable peroxisomes. In both patients plasma levels of pipecolic acid, phytanic acid, trihydroxycoprostanoic acid and dihydroxycoprostanoic acid were elevated. The very long chain fatty acid C26:0 and the C26:0/C22:0 fatty acid ratio were elevated in plasma, but less than in classical Zellweger syndrome. In cultured fibroblasts, deficient acyl-CoA:dihydroxyacetone phosphate acyltransferase and increased concentrations of C26:0 as well as C26:1 very long chain fatty acids were found within the ranges previously established for patients with classical Zellweger syndrome. Particle-bound catalase was absent in fibroblasts. Despite the relatively mild clinical expression the biochemical abnormalities found in these patients are the result of a general peroxisomal dysfunction similar to the changes in classical Zellweger syndrome.

A 9-year-old boy with onychotrichodysplasia and chronic neutropenia is presented. In contrast to cases described earlier, our patient has normal intelligence. The typical features of trichorrhexis nodosa are shown by electronmicroscopic photography. The chronic neutropenia is discussed and supposed to be part of the so-called lazy leucocyte syndrome.

A 13-year-old girl with severe mental retardation, tapetoretinal degeneration, an extinguished electroretinogram and sensoneurinal hearing loss is described. In early life the diagnosis of Zellweger (cerebro-hepato-renal) syndrome was considered because of hypotonia, craniofacial dysmorphia, abnormal liver functions and pipecolic aciduria. Biochemical studies in fibroblasts from the patient revealed a general peroxisomal dysfunction comparable to the findings in Zellweger Syndrome. As the clinical presentation of this patient is essentially different from that in classical Zellweger patients, who usually die early in life, we recommend the study of peroxisomal functions in all patients with severe mental retardation, tapetoretinal degeneration and sensoneurinal hearing loss.