Clinical significance of the size of nucleotide expansion of the HTT gene in patients with Huntington’s disease

Aim: to describe the clinical significance of the number of CAG repeats in exon 1 of the HTT gene in patients with Huntington’s disease in the Russian Federation.
Methods. A total of 1290 DNA samples was obtained from previously collected samples of patients. The number of CAG repeats in the HTT gene was evaluated in the «Laboratory for diagnostics of autoimmune diseases» the Federal State Budgetary Educational Institution of Higher Education Academician I.P. Pavlov First St. Petersburg State Medical University of the Ministry of Healthcare of Russian Federation. Informed consent was obtained from each patient. To evaluate CAG-repeats number in HTT gene, fragment analysis and triplet repeat primed PCR were used. The «Normal» group included patients with number of CAG repeats ≤26. The «Premutation» group consisted of patients who had at least one allele with the number of triplets from 27 to 35 (intermediate alleles, IA). The «Mutation» group included patients with number of CAG repeats ≥36 . Statistical analysis was performed by using the GraphPad Prism 8 program (GraphPad Software Inc., USA).
Results. A total of 659 samples had no expansion, 44 samples had at least one IA, 587 samples had ≥36 CAG repeats. In the «Mutation» group the association between the age of examination in the laboratory and the size of the expansion allele was investigated and an inverse correlation between these parameters was revealed (p< 0.0001 r= 0.4930). In 15 of 32 familial cases, the expansion allele was transmitted to the child. Transmission of the mutation from the father occurred in 86.67% of cases, from the mother − in 13.33% of cases.
Conclusions. Inverse correlation was revealed between age of the patient’s first visit to laboratory and the number of CAG-repeats. The revealed prevalence of intermediate alleles in the population accentuates the importance of studying the characteristics of the clinical course of Huntington’s disease in their carriers.

1. Seliverstov Yu.A., Dranitsyna M.A., Kravchenko M.A., et al. Epidemiologiya bolezni Gentingtona v Rossiyskoy Federatsii. V kn. Bolezn’ Parkinsona i rasstroystva dvizheniy. Rukovodstvo dlya vrachey. Po materialam IV Natsional’nogo kongressa po bolezni Parkinsona i rasstroystvam dvizheniy [Epidemiology of Huntington’s disease in the Russian Federation. In: Parkinson’s disease and movement disorders. Guide for doctors. Based on materials from the IV National Congress on Parkinson’s disease and movement disorders]. 2017; 244-246. (In Russ.)

2. Baig S.S., Strong M., Quarrell O.W. The global prevalence of Huntington’s disease: a systematic review and discussion. Neurodegenerative Disease Management. 2016; 6(4): 331 343.

3. The Huntington’s Disease Collaborative Research Group. A novel gene containing a trinucleotide repeat that is expanded and unstable on Huntington’s disease chromosomes. Cell. 1993; 72: 971-983.

4. Bates G., Harper P.S., Jones L. Huntington’s Disease, 3rd edn. Oxford: Oxford University Press, 2002. 558p.

5. Illarioshkin S.N., Klyushnikov S.A., Vigont V.A., et al. Molecular Pathogenesis in Huntington’s Disease. Biochemistry (Mosc). 2018; 83(9): 1030 1039.

6. Losekoot M., van Belzen M.J., Seneca S., Bauer P., Stenhouse S.A., Barton D.E.; European Molecular Genetic Quality Network (EMQN). EMQN/CMGS best practice guidelines for the molecular genetic testing of Huntington disease. Eur J Hum Genet. 2013; 21(5):480-6.

7. Cannella M., Maglione V., Martino T., et al. New Huntington disease mutation arising from a paternal CAG34allele showing somatic length variation in serially passaged lymphoblasts. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics. 2005; 133B(1): 127–130.

8. Zabnenkova V., Schagina O.A., Galeeva N.M., et al. HTT gene premutation allele frequencies in the Russian Federation. Russian Journal of Genetics. 2018; 54(6): 732-739.

9. Myers R.H. Huntington’s disease genetics. NeuroRx. 2004; 1(2): 255-62.

10. Capiluppi E., Romano L., Rebora P., et al. Late-onset Huntington’s disease with 40–42 CAG expansion. Neurological Sciences. 2020; 41: 869–876.

11. Saudou F., Finkbeiner S., Devys D., et al. Huntingtin acts in the nucleus to induce apoptosis but death does not correlate with the formation of intranuclear inclusions. Cell. 1998; 95: 55-66.

12. Bjelland S., Seeberg E. Mutagenicity, toxicity and repair of DNA base damage induced by oxidation. Mutat. Res. 2003; 531: 37–80.

13. Aziz N.A., Jurgens C.K., Landwehrmeyer G.B., et al. Normal and mutant HTT interact to affect clinical severity and progression in Huntington disease. Neurology. 2009; 73(16): 1280 1285.

14. Kovtun I.V., Liu Y., Bjoras M., et al. OGG1 initiates age-dependent CAG trinucleotide expansion in somatic cells. Nature. 2007; 447: 447–452.

15. Spiro C., Pelletier R., Rolfsmeier M.L., et al. Inhibition of FEN-1 processing by DNA secondary structure at trinucleotide repeats. Mol. Cell. 1999; 4: 1079 1085.

16. McMurray C.T. Mechanisms of trinucleotide repeat instability during human development. Nature Reviews Genetics. 2010; 11(11): 786–799.

17. Erkkinen M.G., Kim M.O., Geschwind M.D. Clinical Neurology and Epidemiology of the Major Neurodegenerative Diseases. Cold Spring Harb Perspect Biol. 2018; 10(4). a033118. doi:10.1101/cshperspect.a033118.

18. Brinkman R.R., Mezei M.M., Theilmann J., et al. The likelihood of being affected with Huntington disease by a particular age, for a specific CAG size. Am J Hum Genet. 1997. 60(5): 1202-1210.

19. Duyao M., Ambrose C., Myers R., et al. Trinucleotide repeat length instability and age of onset in Huntington’s disease. Nature Genetics. 1993; 4(4): 387–392.

20. Langbehn D., Brinkman R., Falush D., et al. A new model for prediction of the age of onset and penetrance for Huntington’s disease based on CAG length. Clinical Genetics. 2004; 65(4): 267–277.

21. Nazarov V.D., Lapin S.V., Gavrichenko A.V., et al. Vyyavleniye ekspansii trinukleotidnykh povtorov pri bolezni Gentingtona. [Investigation of trinucleotides expansion level in Huntington disease with triplet repeats PCR]. Meditsinskaya genetika [Medical Genetics]. 2017;16(3):24-29. (In Russ.)

22. Losekoot M., van Belzen M.J., Seneca S. et al. EMQN/CMGS best practice guidelines for the molecular genetic testing of Huntington disease. Eur J Hum Genet. 2013; 21(5): 480-486.

23. Quarrell O.W., Handley O., O’Donovan K. et al. Discrepancies in reporting the CAG repeat lengths for Huntington’s disease. Eur J Hum Genet. 2012 Jan;20(1): 20-6.

24. Rudenskaya G.E., Savvin D.A., Fedotov V.P., et al. Yuvenil’naya bolezn’ Gentingtona. [Juvenile Huntington’s disease]. Annaly klinicheskoy i eksperimental’noy nevrologii [Annals of Clinical and Experimental Neurology]. 2010; 4(2): 52-58. (In Russ.)

25. Munasipova S.E., Zalyalova Z.A. Kliniko-epidemiologicheskiye aspekty bolezni Gentingtona v Respublike Tatarstan [Clinical and Epidemiological Aspects of Huntington Disease in the Republic of Tatarstan]. Annaly klinicheskoy i eksperimental’noy nevrologii [Annals of Clinical and Experimental Neurology]. 2020; 14(2): 23-28. (In Russ.)

26. Proskokova T.N., Skretnev A.S. Epidemiologiya bolezni Gentingtona v Khabarovskom kraye [Epidemiology of Huntington’s disease in the Khabarovsk Territory]. Annaly klinicheskoy i eksperimental’noy nevrologii [Annals of Clinical and Experimental Neurology]. 2016; 2: 28-32. (In Russ.)

27. Quarrell O., O’Donovan K.L., Bandmann O., et al. The Prevalence of Juvenile Huntington’s Disease: A Review of the Literature and Meta-Analysis. PLoS Curr. 2012; 4:e4f8606b742ef3. doi: 10.1371/4f8606b742ef3.

28. Quarrell O.W., Nance M.A., Nopoulos P., et al. Managing juvenile Huntington’s disease. Neurodegenerative Disease Management. 2013; 3(3): 267-276.

29. Ruocco H., Lopes-Cendes I., Laurito T., et al. Clinical presentation of juvenile Huntington disease. Arq. Neuropsiquiatr. 2006; 64: 5–9.

30. Squitieri F., Cannella M., Giallonardo P., et al. Onset and pre-onset studies to define the Huntington’s disease natural history. Brain Research Bulletin. 2001; 56(3-4): 233–238.

31. Ajitkumar A., De Jesus O. Huntington Disease. 2022 Oct 7. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. 2022; PMID: 32644592.

32. Nikitina M.A., Bragina E.Yu., Nazarenko M.S., et al. Atipichnoye techeniye bolezni Parkinsona s klinicheskimi proyavleniyami bolezni Gentingtona u patsiyentki s allelem 27 CAG povtorov v gene HTT [Atypical course of Parkinson’s disease with clinical manifestations of Huntington’s disease in a patient with an allele of 27 CAG repeats in the HTT gene]. Byulleten’ sibirskoy meditsiny [Bulletin of Siberian Medicine]. 2020;19(4):235-240. (In Russ.)

33. Yudina G.K., Solovykh N.N., Sholomov I.I. Kliniko-geneticheskaya kharakteristika nasledstvennykh ekstrapiramidnykh zabolevaniy v Saratovskoy oblasti [Clinical and genetic characteristics of hereditary extrapyramidal diseases in the Saratov region]. Zhurnal Nevrologii i Psikhiatrii imeni S.S. Korsakova [S.S. Korsakov Journal of Neurology and Psychiatry]. 2005; 5: 52–55. (In Russ.)

34. Costa M. do C., Magalhães P., Guimarães L., et al. The CAG repeat at the Huntington disease gene in the Portuguese population: insights into its dynamics and to the origin of the mutation. Journal of Human Genetics. 2005; 51(3): 189-195.

35. Ha A.D., Beck C.A., Jankovic J. Intermediate CAG repeats in Huntington’s disease: Analysis of COHORT. Tremor Other Hyperkinet Mov. 2012; 2: tre 02-64-287-4.

36. Kay C., Collins J.A., Miedzybrodzka Z., et al. Huntington disease reduced penetrance alleles occur at high frequency in the general. Neurology. 2016; 87: 282–288.

37. Downing N.R., Lourens S., De Soriano I., et al. PREDICT-HD Investigators and Coordinators of the Huntington Study Group. Phenotype Characterization of HD Intermediate Alleles in PREDICT-HD. J Huntingtons Dis. 2016; 5(4): 357-368.

38. Cubo E., Ramos-Arroyo M.A., Martinez-Horta S., et al. Clinical manifestations of intermediate allele carriers in Huntington disease. Neurology. 2016; 87(6): 571-578.

39. Killoran A., Biglan K.M., Jankovic J., et al. Characterization of the Huntington intermediate CAG repeat expansion phenotype in PHAROS. Neurology. 2013; 80(22): 2022 2027.

40. Menéndez-González M., Clarimón J., Allende I.R., et al. HTT gene intermediate alleles in neurodegeneration: Evidence for association with Alzheimer’s disease. Neurobiol. Aging. 2019; 76: 215.e9–215. e14. DOI: 10.1016/j.neurobiolaging.2018.11.014.

41. Ramos E.M., Gilli T., Mysore J.S., et al. Prevalence of Huntington’s disease gene CAG trinucleotide repeat alleles in patients with bipolar disorder. Bipolar Disorders, 2015; 17(4): 403 408.

42. Perlis R.H., Smoller J.W., Mysore J., et al. Prevalence of Incompletely Penetrant Huntington’s Disease Alleles Among Individuals With Major Depressive Disorder. American Journal of Psychiatry. 2010; 167(5): 574-579.

43. Telenius H., Almqvist E., Kremer B., et al. Somatic mosaicism in sperm is associated with intergenerational (CAG)n changes in Huntington disease. Human Molecular Genetics. 1995; 4(2): 189-195.

44. Chena Y.-S., Hua T.-M., Wanga Y.-Y., Wu C.-L. A case of Huntington’s disease presenting with psychotic symptoms and rapid cognitive decline in the early stage. European Journal of Psychiatry. 2019. 36(1): 65-66.

45. Morozov I.I., Emelyanov Yu.V. Klinicheskiy sluchay bolezni Gentingtona v psikhiatricheskoy praktike [Clinical case of Huntington’s disease in psychiatric practice]. Zdravookhraneniye Yugry: opyt i innovatsii [Healthcare of Ugra: experience andinnovations]. 2017;: 62-65. (In Russ.)

46. Kaplan S., Itzkovitz S., Shapiro E. A Universal Mechanism Ties Genotype to Phenotype in Trinucleotide Diseases. PLoS Computational Biology. 2007; 3(11): e235. doi: 10.1371/journal.pcbi.0030235.

47. Illarioshkin S.N., Igarashi S., Onodera O., et al. Trinucleotide repeat length and rate of progression of Huntington’s disease. Annals of Neurology. 1994; 36(4): 630–635.

48. Folstein S.E. Huntington’s disease: A disorder of families. Johns Hopkins University Press. 1989. 251p.

49. Agostinho L.A., Dos Santos S.R., Alvarenga R.M., et al. A systematic review of the intergenerational aspects and the diverse genetic profiles of Huntington’s disease. Genet Mol Res. 2013; 12(2): 1974-1981.

50. Goldberg Y.P., Kremer B., Andrew S.E., et al. Molecular analysis of new mutations for Huntington’s disease: intermediate alleles and sex of origin effects. Nature Genetics. 1993; 5(2): 174–9179.

51. Kremer B., Almqvist E., Theilmann J., et al. Sex-dependent mechanisms for expansions and contractions of the CAG repeat on affected Huntington disease chromosomes. Am J Hum Genet. 1995; 57(2): 343-50.

52. Semaka A., Hayden M.R. Evidence-based genetic counselling implications for Huntington disease intermediate allele predictive test results. Clin. Genet. 2014; 85(4): 303 311.