ORPHA: 168491, 79264; DO: 0110723;
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
Gene/Locus |
Gene/Locus MIM number |
|---|---|---|---|---|---|---|
| 8p23.3 | Ceroid lipofuscinosis, neuronal, 8 | 600143 | Autosomal recessive | 3 | CLN8 | 607837 |
A number sign (#) is used with this entry because neuronal ceroid lipofuscinosis-8 (CLN8) is caused by homozygous or compound heterozygous mutation in the CLN8 gene (607837) on chromosome 8p23.
See also the Northern epilepsy variant of CLN8 (610003), an allelic disorder with a different phenotype.
The neuronal ceroid lipofuscinoses (NCL; CLN) are a clinically and genetically heterogeneous group of neurodegenerative disorders characterized by the intracellular accumulation of autofluorescent lipopigment storage material in different patterns ultrastructurally. The lipopigment patterns observed most often in CLN8 comprise mixed combinations of 'granular,' 'curvilinear,' and 'fingerprint' profiles (Mole et al., 2005).
For a general phenotypic description and a discussion of genetic heterogeneity of CLN, see CLN1 (256730).
Wheeler et al. (1999) reported 6 Turkish families with a phenotype similar to that of other forms of late-onset infantile CLN (see, e.g., CLN2, 204500; CLN5, 256731; CLN6, 601780), but who did not map to any known CLN loci. Four of the 6 families reported by Wheeler et al. (1999) were later found by Mitchell et al. (2001) to show linkage to the CLN8 gene on chromosome 8p23, and Ranta et al. (2004) identified mutations in the CLN8 gene in affected members from all 4 of these families (see, e.g., 607837.0003; 607837.0004), thus confirming that they in fact had CLN8.
Topcu et al. (2004) reported the so-called Turkish variant of late-infantile CLN in 17 of 28 Turkish patients. Most of the families were consanguineous. The mean age at disease onset was 5.1 years (range, 2 to 7 years), with seizures or motor impairment as the most common presenting symptom. As the disease progressed, mental regression, myoclonus, speech impairment, loss of vision, and personality disorders developed, and most of the patients became nonambulatory within 2 years after onset. The features distinguishing the Turkish variant from CLN2 and CLN3 included a more severe course regarding seizures, the presence of condensed fingerprint profiles on electron microscopic examination of lymphocytes, and lack of vacuolated lymphocytes.
Cannelli et al. (2006) reported 3 unrelated Italian patients with CLN8. Clinical features included delayed psychomotor development, seizures, myoclonus, and progressive loss of vision. Ultrastructural studies showed osmiophilic inclusions in curvilinear and fingerprint profiles in various tissues. Brain MRI showed cerebral and cerebellar atrophy. One of the patients was born of consanguineous parents.
Allen et al. (2012) reported a 5.5-year-old Irish boy, born of unrelated parents, with CLN8. He had early global developmental delay with suspected autism. At age 4 years, he developed clumsiness, deterioration of speech, and progressive social withdrawal. He later developed seizures and became immobile. Physical examination showed cognitive delay, visual impairment, jerky ocular pursuit, brisk deep tendon reflexes, and broad-based gait. There were no dysmorphic features. Visual evoked responses were delayed, and electroretinogram was absent. Brain MRI revealed hyperintensity in the white matter and cerebellar atrophy. Electron microscopic examination of lymphocytes showed membrane-bound fingerprint profiles without vacuolization and a mixture of curvilinear and rectilinear profiles, with small fingerprint stacks in sweat gland epithelia, blood vessel endothelia, and smooth muscle cells on skin biopsy. Molecular testing identified compound heterozygosity for a truncating mutation in the CLN8 gene inherited from the unaffected father and a de novo terminal deletion of 8p23.3 including the CLN8 gene on the maternal allele.
Mitchell et al. (2001) detected linkage and homozygosity in the vicinity of the CLN8 locus in 4 Turkish families with the so-called Turkish variant of late-infantile CLN. Ranta et al. (2004) extended the Turkish vLINCL family panel to 18 families and found linkage to the CLN8 locus in 9 families. The other 9 families were excluded from CLN8 by lack of homozygosity in the 8p23 region.
The transmission pattern of CLN8 in the families reported by Ranta et al. (2004) was consistent with autosomal recessive inheritance.
Ranta et al. (2004) identified 4 homozygous mutations in the CLN8 gene (see, e.g., 607837.0002-607837.0004) in affected members of 9 families with the so-called Turkish variant of late-infantile CLN, 4 of whom were reported by Wheeler et al. (1999) and Mitchell et al. (2001), and 5 of whom were reported by Topcu et al. (2004). The findings indicated that the disorder is allelic to Finnish Northern epilepsy variant of CLN8. There was no apparent genotype/phenotype correlation among the Turkish patients with CLN8 mutations, although the authors noted that the phenotype was distinct from that of Finnish Northern epilepsy patients.
In 3 unrelated Italian patients with CLN8, Cannelli et al. (2006) identified homozygous or compound heterozygous mutations in the CLN8 gene (see, e.g., 607837.0005 and 607837.0006, respectively).
In a naturally occurring mouse model of NCL, termed 'motor neuron degeneration' (mnd) mouse (Bronson et al., 1993), Ranta et al. (1999) identified a homozygous 1-bp insertion (267-268insC at codon 90) in the Cln8 gene, predicting a frameshift and a truncated protein. This was the first description of the molecular basis of a naturally occurring animal model for NCL.
Katz et al. (2005) identified a leu164-to-pro (L164P) mutation in the Cln8 gene in English setter dogs with autosomal recessive NCL.
In a mixed breed dog with Australian Shepherd and Blue Heeler ancestry, Guo et al. (2014) reported a G-to-A transition at nucleotide c.585 in the Cln8 gene, resulting in a nonsense mutation at codon 195 instead of the expected tryptophan. The dog had neurologic signs characteristic of CLN8 starting at 8 months of age. The authors found the mutation in heterozygosity or homozygosity in 7 of 1,488 archived Australian Shepherd DNA samples. All 3 dogs homozygous for the A allele exhibited clinical signs of NCL, and in 2 of them NCL was confirmed by postmortem evaluation of brain tissue.
Allen, N. M., O'hlci, B., Anderson, G., Nestor, T., Lynch, S. A., King, M. D. Variant late-infantile neuronal ceroid lipofuscinosis due to a novel heterozygous CLN8 mutation and de novo 8p23.3 deletion. (Letter) Clin. Genet. 81: 602-604, 2012. [PubMed: 22220808] [Full Text: https://doi.org/10.1111/j.1399-0004.2011.01777.x]
Bronson, R. T., Lake, B. D., Cook, S., Taylor, S., Davisson, M. T. Motor neuron degeneration of mice is a model of neuronal ceroid lipofuscinosis (Batten's disease). Ann. Neurol. 33: 381-385, 1993. [PubMed: 7683855] [Full Text: https://doi.org/10.1002/ana.410330408]
Cannelli, N., Cassandrini, D., Bertini, E., Striano, P., Fusco, L., Gaggero, R., Specchio, N., Biancheri, R., Vigevano, F., Bruno, C., Simonati, A., Zara, F., Santorelli, F. M. Novel mutations in CLN8 in Italian variant late infantile neuronal ceroid lipofuscinosis: another genetic hit in the Mediterranean. Neurogenetics 7: 111-117, 2006. [PubMed: 16570191] [Full Text: https://doi.org/10.1007/s10048-005-0024-y]
Guo, J., Johnson, G. S., Brown, H. A., Provencher, M. L., da Costa, R. C., Mhlanga-Mutangadura, T., Taylor, J. F., Schnabel, R. D., O'Brien, D. P., Katz, M. L. A CLN8 nonsense mutation in the whole genome sequence of a mixed breed dog with neuronal ceroid lipofuscinosis and Australian Shepherd ancestry. Molec. Genet. Metab. 112: 302-309, 2014. [PubMed: 24953404] [Full Text: https://doi.org/10.1016/j.ymgme.2014.05.014]
Katz, M. L., Khan, S., Awano, T., Shahid, S. A., Siakotos, A. N., Johnson, G. S. A mutation in the CLN8 gene in English setter dogs with neuronal ceroid-lipofuscinosis. Biochem. Biophys. Res. Commun. 327: 541-547, 2005. [PubMed: 15629147] [Full Text: https://doi.org/10.1016/j.bbrc.2004.12.038]
Mitchell, W. A., Wheeler, R. B., Sharp, J. D., Bate, S. L., Gardiner, R. M., Ranta, U. S., Lonka, L., Williams, R. E., Lehesjoki, A.-E., Mole, S. E. Turkish variant late infantile neuronal ceroid lipofuscinosis (CLN7) may be allelic to CLN8. Europ. J. Paediat. Neurol. 5 (suppl. A): 21-27, 2001. [PubMed: 11589000] [Full Text: https://doi.org/10.1053/ejpn.2000.0429]
Mole, S. E., Williams, R. E., Goebel, H. H. Correlations between genotype, ultrastructural morphology and clinical phenotype in the neuronal ceroid lipofuscinoses. Neurogenetics 6: 107-126, 2005. [PubMed: 15965709] [Full Text: https://doi.org/10.1007/s10048-005-0218-3]
Ranta, S., Topcu, M., Tegelberg, S., Tan, H., Ustubutun, A., Saatci, I., Dufke, A., Enders, H., Pohl, K., Alembik, Y., Mitchell, W. A., Mole, S. E., Lehesjoki, A.-E. Variant late infantile neuronal ceroid lipofuscinosis in a subset of Turkish patients is allelic to Northern epilepsy. Hum. Mutat. 23: 300-305, 2004. [PubMed: 15024724] [Full Text: https://doi.org/10.1002/humu.20018]
Ranta, S., Zhang, Y., Ross, B., Lonka, L., Takkunen, E., Messer, A., Sharp, J., Wheeler, R., Kusumi, K., Mole, S., Liu, W., Soares, M. B., de Fatima Bonaldo, M., Hirvasniemi, A., de la Chapelle, A., Gilliam, T. C., Lehesjoki, A.-E. The neuronal ceroid lipofuscinoses in human EPMR and mnd mutant mice are associated with mutations in CLN8. Nature Genet. 23: 233-236, 1999. [PubMed: 10508524] [Full Text: https://doi.org/10.1038/13868]
Topcu, M., Tan, H., Yalnizoglu, D., Usubutun, A., Saatci, I., Aynaci, M., Anlar, B., Topaloglu, H., Turanli, G., Kose, G., Aysun, S. Evaluation of 36 patients from Turkey with neuronal ceroid lipofuscinosis: clinical, neurophysiological, neuroradiological and histopathologic studies. Turk. J. Pediatr. 46: 1-10, 2004. [PubMed: 15074367]
Wheeler, R. B., Sharp, J. D., Mitchell, W. A., Bate, S. L., Williams, R. E., Lake, B. D., Gardiner, R. M. A new locus for variant late neuronal ceroid lipofuscinosis--CLN7. Molec. Genet. Metab. 66: 337-338, 1999. [PubMed: 10191125] [Full Text: https://doi.org/10.1006/mgme.1999.2804]