A CLN5 mutation causing an atypical neuronal ceroid lipofuscinosis of juvenile onset.

Three related patients from Colombia presented with a juvenile-onset neuronal ceroid lipofuscinosis. Electron microscopy of one case showed condensed fingerprint profiles, and genetic analyses identified a novel missense mutation in CLN5. The authors demonstrate the existence of pathogenic CLN5 mutations outside northern Europe and that mutations in this gene can lead to an atypical late-onset neuronal ceroid lipofuscinosis disease, in addition to the late infantile form first described in Finland.

Neuronal ceroid lipofuscinosis: late infantile or Jansky Bielschowsky type--re-revisited.

Among the now eight genetic types of neuronal ceroid-lipofuscinoses (NCL), CLN1 to CLN8, CLN2 is considered classic late-infantile NCL. It was originally described by Jansky in a family of eight children with four of them affected [Jansky J (1908) Sborn Lék 13:165-196] and, subsequently, by Bielschowsky in a family of three children each of whom was affected, and, hence, termed Jansky-Bielschowsky type of NCL. Earlier, archival studies of Bielschowsky's original post-mortem tissue blocks had documented accumulation of autofluorescent lipopigments with a curvilinear ultrastructure. In a subsequent study, described here, immunohistochemical absence of the CLN2-related lysosomal enzyme tripeptidyl peptidase-I and two heterozygous mutations in the CLN2 gene could be demonstrated in these archival tissues, further corroborating the identity of Bielschowsky's familial disorder and CLN2 described by M. Bielschowsky at the beginning of the last century. Furthermore, these immunohistochemical and mutational investigations underscore the value of archival tissue studies.

Morphological studies on CLN2.

Electron microscopic, fluorescence microscopic, and immunohistochemical studies earlier performed on archival cerebral tissue from Max Bielchowsky's original three patients revealed curvilinear bodies rich in subunit C of mitochondrial ATP synthase (SCMAS). Recent progress in the elucidation of CLN2, i.e. identification of the defective lysosomal enzyme tripeptidyl-peptidase I (TPP-I) and mutations in the CLN2 gene have further corroborated earlier data. Immunohistochemically the absence of the TPP-I protein could be confirmed in the archival tissues using pathological controls. Unlike biochemistry, immunohistochemistry enables examination of these archival tissues elucidating the causative defect. Complementary molecular studies identified mutations in the CLN2 gene in the archival tissues and thereby convincingly demonstrated that these three children truly had classic late infantile neuronal ceroid lipofuscinosis (LINCL), now called CLN2. This archival study documents the possibilities to revalidate disease-specific original nosologic reports. Chloroquine is toxic to lysosomal enzymes and results in lysosomal storage. The material is autofluorescent and gives the ultrastructural pattern of curvilinear profiles, thus resembling classic late infantile NCL, representing a good experimental model. In humans chloroquine therapy may cause a myopathy (and retinopathy) and, as recently suggested, an encephalopathy marked by lysosomal accretion in several cell types including neurons. Immunohistochemically, SCMAS also accumulates, further strengthening morphologic similarity between LINCL and human chloroquine intoxication.

Turkish variant late infantile neuronal ceroid lipofuscinosis (CLN7) may be allelic to CLN8.

One variant form of late infantile neuronal ceroid lipofuscinosis (LINCL) is found predominantly within the Turkish population (CLN7). Exclusion mapping showed that CLN7 was not an allelic variant of known NCL loci (CLN1, CLN2, CLN3, CLN5 or CLN6). Using the method of homozygosity mapping, a genome-wide search was undertaken and a total of 358 microsatellite markers were typed at an average distance of about 10 cM. A region of shared homozygosity was identified on chromosome 8p23. This telomeric region contained the recently identified CLN8 gene. A missense mutation in CLN8 causes progressive epilepsy with mental retardation (EPMR) or Northern epilepsy, which has so far been reported only from Finland and is now classified as an NCL. The mouse model mnd has been shown to carry a 1 bp insertion in the orthologous Cln8 gene. Statistically significant evidence for linkage was obtained in this region, with LOD scores > 3, assuming either homogeneity or heterogeneity. Flanking recombinants defined a critical region of 14 cM between D8S504 and D8S1458 which encompasses CLN8. This suggests that Turkish variant LINCL, despite having an earlier onset and more severe phenotype, may be an allelic variant of Northern epilepsy. However mutation analysis has not so far identified a disease causing mutation within the coding or non-coding exons of CLN8 in the families. The Turkish variant LINCL disease-causing mutation remains to be delineated.

Analysis of candidate genes in the CLN6 critical region using in silico cloning.

CLN6, the gene for variant late infantile neuronal ceroid lipofuscinosis, was mapped to a 4 cM region on chromosome 15q22-23. Subsequently the critical region was narrowed to less than 1 cM between microsatellite markers D15S988 and D15S1000 by additional marker typing in an expanded family resource. A physical map was constructed across this region using YAC and PAC clones and sequence was generated from two PAC clones. This sequence was analysed together with overlapping sequence generated by the Human Genome Project to identify genes within the region using an in silico cloning approach. In all, 29 genes have been identified and 18 have been analysed for mutations by direct sequencing. This powerful new approach will lead to the identification of CLN6.

Exclusion of late infantile neuronal ceroid lipofuscinosis (LINCL) in a fetus by assay of tripeptidyl peptidase I in chorionic villi.

We report the exclusion of late infantile neuronal ceroid lipofuscinosis in a fetus by assay of tripeptidyl peptidase I activity and by mutational analysis in chorionic villi. This is the first pregnancy at risk for LINCL to be monitored by enzyme assay. No morphological abnormalities were detected.

Genetic and physical mapping of the CLN6 gene on chromosome 15q21-23.

CLN6, the gene for a variant late infantile neuronal ceroid lipofuscinosis, has been mapped to chromosome 15q21-23 by homozygosity mapping. At present the family resource consists of 31 families. By the analysis of additional polymorphic markers in this resource the critical region has been narrowed down from 12 cM to less than 4 cM. A physical map is being constructed using YAC and PAC clones as a prerequisite to transcript mapping.

A new locus for variant late infantile neuronal ceroid lipofuscinosis-CLN7.

To date two genes are known to be involved in variant LINCL, CLN5 and CLN6, which map to chromosomes 13q21 and 15q21-23. A subset of Turkish families with a variant phenotype has been identified. Affected individuals have curvilinear bodies and fingerprint profiles on EM but are recombinant at CLN5 and CLN6. These families appear to represent a new locus. Homozygosity mapping is being used to map this locus, which has been designated CLN7.

Loci for classical and a variant late infantile neuronal ceroid lipofuscinosis map to chromosomes 11p15 and 15q21-23.

The childhood neuronal ceroid lipofuscinoses (NCLs) are a group of autosomal recessive neurodegenerative disorders characterised by progressive visual failure, neurodegeneration, epilepsy and the accumulation of an autofluorescent lipopigment in neurones and other cells. Three main subtypes have been identified according to age of onset, clinical features and ultrastructural morphology. These are infantile NCL (INCL; CLN1), classical late infantile NCL (LINCL; CLN2) and juvenile NCL (JNCL; CLN3). Several atypical forms of late infantile NCL (LINCL) have also been described including a Finnish variant LINCL (CLN5). The CLN2 gene has been excluded from the CLN1, CLN3 and CLN5 loci. A genome search was initiated using a homozygosity mapping strategy in five classical LINCL and two variant LINCL consanguineous families. A common region of homozygosity was identified on chromosome 11p15 in two of the classical families. Analysis of a further 33 classical LINCL families supported linkage in this region (Zmax = 3.07 at theta = 0.06 at D11S1338). A common region of homozygosity was also observed on chromosome 15q21-23 in the two variant LINCL families. Extension of the analysis to include a further seven families of identical ultrastructural phenotype established linkage to this region (Zmax = 6.00 at theta = 0.00 at D15S1020).

Radiology-pathology conference: Robert Wood Johnson Medical School. Eosinophilic granuloma of the lung.

Eosinophilic granuloma of the lung is a nodular infiltration of the interstitium of the lung by histiocytes, plasma cells, lymphocytes, and eosinophils. While radiologic findings of nodules and small cystic spaces of the upper lung zones are present, surgical biopsy is required for diagnosis.

Linkage analysis of late-infantile neuronal ceroid-lipofuscinosis.

The neuronal ceroid-lipofuscinoses (NCL) are a group of neurodegenerative disorders with an autosomal-recessive pattern of inheritance. There are 3 main categories of childhood NCL, namely, infantile, late-infantile, and juvenile NCL. These can be distinguished on the basis of age of onset, clinical course, and histopathology. A number of variant forms of NCL have also been described, and these show symptoms intermediary between the main classical forms. The genes for both the infantile and juvenile forms of NCL have previously been mapped to chromosome areas 1p32 and 16p12, respectively. The gene for late-infantile NCL (LINCL), CLN2, has been excluded from both these loci, but its location is as yet unknown. Recently, CLN5, the gene for the Finnish variant form of LINCL, was mapped to 13q21.1-32. Using the 3 microsatellite markers which were most tightly linked to CLN5, we have excluded CLN2 from this region using a subset of 17 families. Thus, CLN2 represents a fourth distinct genetic locus involved in the pathogenesis of NCL.

Eosin-5-maleimide inhibits red cell Cl- exchange at a noncompetitive site that senses band 3 conformation.

Eosin-5-maleimide (EM) has been used as a fluorescent probe for the external-facing transport site of the human erythrocyte band 3 protein. Changes in chloride concentration at both sides of the membrane have no significant effect on the inhibitory potency of EM as a reversible inhibitor of Cl- exchange at 0 degrees C, however, demonstrating that it is not a competitive inhibitor. The affinity of EM for the form of band 3 with the transport site facing outward is approximately five times greater than for the form with the transport site facing the cytoplasm; binding of iodide to the external transport site causes no statistically significant decrease in affinity for EM. Eosin, without the maleimide moiety, is a slightly more potent inhibitor than is EM. Erythrosin, an analogue with four iodide atoms replacing the four bromide atoms in eosin, is a much more potent inhibitor, with a half-inhibitory concentration of only 3.1 microM, > 30 times lower than that of EM. Neither eosin nor erythrosin inhibition is affected by changes in chloride concentration as would be expected for a competitive inhibitor. Thus EM and the other eosin derivatives bind to a site separate from the external transport site, but one that is affected by the changes of transport site conformation from the inward-facing to the outward-facing state.

Toxoplasma serology in Zambian and Ugandan patients infected with the human immunodeficiency virus.

In the USA and Europe, toxoplasmosis is well recognized as an important cause of morbidity and mortality among immunocompromised individuals. Toxoplasma gondii has been shown to be a common opportunistic infection in patients infected with the human immunodeficiency virus (HIV) in the USA and Europe with published estimates ranging from 20% to 80%. The importance of Toxoplasma infection in East Africa has not yet been defined. The seroprevalence rates of toxoplasmosis in Zambian and Ugandan patients were determined using the dye test (DT) and the latex agglutination test (LAT). The geographical variation in seroprevalence rates noted in western countries was also found in these African countries, with Zambia showing significantly lower rates than Uganda. 34% of Ugandan (64/186) and 4% of Zambian (8/187) patients infected with HIV, compared with 27% of Ugandan (26/93) and 11% of Zambian (20/189) HIV-negative persons, had anti-Toxoplasma immunoglobulin G antibodies. With the LAT, 13% of the Ugandan and 7% of the Zambian sera gave a false positive result. The relevance of Toxoplasma serology in Africa is discussed.

Toxoplasma serology in Zambian and Ugandan patients infected with the human immunodeficiency virus

In the USA and Europe; toxoplasmosis is well recognized as an important cause of morbidity and mortality among immunocompromised individuals. Toxoplasma gondii has been shown to be a common opportunistic infection in patients infected with the human immunodeficiency virus (HIV) in the USA and Europe with published estimates ranging from 20pc to 80pc. The importance of Toxoplasma infection in East Africa has not yet been defined. The seroprevalence rates of toxoplasmosis in Zambian and Ugandan patients were determined using the dye test (DT) and the latex agglutination test (LAT). The geographical variation in seroprevalence rates noted in western countries was also found in these African countries; with Zambia showing significantly lower rates than Uganda. 34pc of Ugandan (64/186) and 4pc of Zambian (8/187) patients infected with HIV; compared with 27pc of Ugandan (26/93) and 11pc of Zambian (20/189) HIV-negative persons; had anti-Toxoplasma immunoglobulin G antibodies. With the LAT; 13pc of the Ugandan and 7pc of the Zambian sera gave a false positive result. The relevance of Toxoplasma serology in Africa is discussed