Folate gene polymorphisms CBS 844ins68 and RFC1 A80G and risk of Down syndrome offspring in young Iranian women: A cross-sectional study


Background: Cytogenetics and association studies showed that folate gene polymorphisms can increase the risk of chromosomal nondisjunction and aneuploidies. The folate-metabolizing gene polymorphisms in Down syndrome mothers (DSM) have been assessed in a variety of populations. Reduced folate carrier 1 (RFC1) and cystathionine beta-synthase (CBS) are key enzymes in folate metabolism.

Objective: 2 common polymorphisms, CBS 844ins68 and RFC1 A80G, were analyzed to determine their probable risk for having Down syndrome (DS) babies in young mothers of Khuzestan province, Iran.

Materials and Methods: This study was conducted on 100 mothers who had trisomy 21 DS children. 100 age- and ethnic-matched mothers with at least 2 healthy children and no history of abnormal pregnancies were considered as control. The samples were collected from all the mothers from June 2019 to April 2021. Genomic DNA was extracted from peripheral blood. The CBS-844ins68 and RFC1-A80G were genotyped using polymerase chain reaction-electrophoresis and restriction fragment length polymorphism, respectively.

Results: The frequency of RFC1 AG and GG genotypes in DSM was significantly higher than the control mothers (odds ratio [OR] of 2.38 and 3.07, respectively). The heterozygote genotype of CBS 844ins68 was significantly more prevalent among DSM than the control (OR: 2.419). The OR was significantly increased to 6.667 when the homozygote of both variants was found together.

Conclusion: Studying polymorphisms possibly increases the susceptibility of having a DS child. However, ethnicity, nutrition, and epistatic interactions are considerable factors to be evaluated in future studies.

Key words: Down syndrome, Folic acid, Polymorphism, CBS, RFC1.

[1] Moyer AJ, Gardiner K, Reeves RH. All creatures great and small: New approaches for understanding down syndrome genetics. Trends Genet 2021; 37: 444–459.

[2] Antonarakis SE, Skotko BG, Rafii MS, Strydom A, Pape SE, Bianchi DW, et al. Down syndrome. Nat Rev Dis Primers 2020; 6: 9.

[3] James SJ, Pogribna M, Pogribny IP, Melnyk S, Hine RJ, Gibson JB, et al. Abnormal folate metabolism and mutation in the methylenetetrahydrofolate reductase gene may be maternal risk factors for Down syndrome. Am J Clin Nutr 1999; 70: 495–501.

[4] Ginani CTA, da Luz JRD, de Medeiros KS, Sarmento ACA, Coppedè F, das Graças Almeida M. Association of C677T and A1298C polymorphisms of the MTHFR gene with maternal risk for Down syndrome: A meta-analysis of casecontrol studies. Mutat Res Rev Mutat Res 2023; 792: 108470.

[5] Halder P, Pal U, Ganguly A, Ghosh P, Ray A, Sarkar S, et al. Genetic aetiology of Down syndrome birth: Novel variants of maternal DNMT3B and RFC1 genes increase risk of meiosis II nondisjunction in the oocyte. Mol Genet Genomics 2023; 298: 293–313.

[6] Yi K, Ma Y-H, Wang W, Zhang X, Gao J, He S-E, et al. The roles of reduced folate carrier-1 (RFC1) A80G (rs1051266) polymorphism in congenital heart disease: A meta-analysis. Med Sci Monit 2021; 27: e929911.

[7] Romano M, Marcucci R, Buratti E, Ayala YM, Sebastio G, Baralle FE. Regulation of 3′ splice site selection in the 844ins68 polymorphism of the cystathionine B-synthase gene. J Biol Chem 2002; 277: 43821–43829.

[8] ElGindy HA, Kotb MA, Mohamed MF, Abuelhamd WA, Alsabagh NN, Anis N, et al. Non-disjunction of chromosome 21 in the young mother at conception. Pediatric Sci J 2022; 2: 164–169.

[9] Gelineau−van Waes J, Heller S, Bauer LK, Wilberding J, Maddox JR, Aleman F, et al. Embryonic development in the reduced folate carrier knockout mouse is modulated by maternal folate supplementation. Birth Defects Res A Clin Mol Teratol 2008; 82: 494–507.

[10] Chango A, Emery-Fillon N, de Courcy GP, Lambert D, Pfister M, Rosenblatt DS, et al. A polymorphism (80G-> A) in the reduced folate carrier gene and its associations with folate status and homocysteinemia. Mol Genet Metab 2000; 70: 310–315.

[11] Imani MM, Mozaffari HR, Sharifi R, Sadeghi M. Polymorphism of reduced folate carrier 1 (A80G) and non-syndromic cleft lip/palate: A systematic review and meta-analysis. Arch Oral Biol 2019; 98: 273–279.

[12] Scala I, Granese B, Sellitto M, Salomè S, Sammartino A, Pepe A, et al. Analysis of seven maternal polymorphisms of genes involved in homocysteine/folate metabolism and risk of Down syndrome offspring. Genet Med 2006; 8: 409–416.

[13] Farjadian Sh, Ota M, Inoko H, Ghaderi A. The genetic relationship among Iranian ethnic groups: An anthropological view based on HLA class II gene polymorphism. Mol Biol Rep 2009; 36: 1943–1950.

[14] Fernandes DM, Mittnik A, Olalde I, Lazaridis I, Cheronet O, Rohland N, et al. The spread of steppe and Iranian-related ancestry in the islands of the western Mediterranean. Nat Ecol Evol 2020; 4: 334–345.

[15] Suresh RV, Udupa AS, Lingaiah K, Polapalli SK, Ramachandra NB. Association of RFC1 A80G gene polymorphism with advanced maternal age in risk of Down syndrome. Cur Med Res Pract 2017; 7: 6–10.

[16] Chaubey G, Ayub Q, Rai N, Prakash S, Mushrif-Tripathy V, Mezzavilla M, et al. “Like sugar in milk”: Reconstructing the genetic history of the Parsi population. Genome Biol 2017; 18: 110.

[17] Turkyilmaz A, Simsek S, Diclehan O, Tekeş S, Hilmi I. Cystathionine synthase T833C/844ins68 Polymorphism: A family-based study on down syndromes children. Int Arch Med Res 2011; 2: 54–56.

[18] Tsai MY, Bignell M, Schwichtenberg K, Hanson NQ. High prevalence of a mutation in the cystathionine betasynthase gene. Am J Hum Genet 1996; 59: 1262–1267.

[19] Sharp L, Little J. Polymorphisms in genes involved in folate metabolism and colorectal neoplasia: A HuGE review. Am J Epidemiol 2004; 159: 423–443.

[20] Franco R, Maffei F, Lourenço D, Piccinato C, Morelli V, Thomazini I, et al. The frequency of 844ins68 mutation in the cystathionine beta-synthase gene is not increased in patients with venous thrombosis. Haematologica 1998; 83: 1006–1008.

[21] Dutta S, Sinha S, Chattopadhyay A, Gangopadhyay PK, Mukhopadhyay J, Singh M, et al. Cystathionine B-synthase T833C/844INS68 polymorphism: A family-based study on mentally retarded children. Behav Brain Funct 2005; 1: 25.

[22] Senemar S, Doroudchi M, Pezeshki AM, Bazrgar M, TorabJahromi A, Ghaderi A. Frequency of cystathionine B- synthase 844INS68 polymorphism in Southern Iran. Mol Biol Rep 2009; 36: 353–356.

[23] Fintelman-Rodrigues N, Corrêa J, Santos J, Pimentel M, Santos-Rebouças C. Investigation of CBS, MTR, RFC-1 and TC polymorphisms as maternal risk factors for Down syndrome. Dis Markers 2009; 26: 155–161.

[24] Chango A, Fillon-Emery N, Mircher C, Bléhaut H, Lambert D, Herbeth B, et al. No association between common polymorphisms in genes of folate and homocysteine metabolism and the risk of Down’s syndrome among French mothers. Br J Nutr 2005; 94: 166–169.

[25] Izci Ay O, Ay ME, Erdal ME, Cayan F, Tekin S, Soylemez F, et al. Folate metabolism gene polymorphisms and risk for down syndrome offspring in Turkish women. Genet Test Mol Biomarkers 2015; 19: 191–197.

[26] Desai M, Chauhan J. Analysis of polymorphisms in genes involved in folate metabolism and its impact on Down syndrome and other intellectual disability. Meta Gene 2017; 14: 24–29.

[27] Biselli JM, Brumati D, Frigeri VF, Zampieri BL, GoloniBertollo EM, Pavarino-Bertelli ÉC. Polimorfismos do gene carregador de folato reduzido (RFC1) A80G e transcobalamina 2 (TC2) C776G na etiologia da síndrome de Down. Sao Paulo Med J 2008; 126: 329–332.

[28] Neagos D, Cretu R, Tutulan-Cunita A, Stoian V, Bohiltea LC. RFC-1 gene polymorphism and the risk of Down syndrome in romanian population. Maedica 2010; 5: 280–285.

[29] Lie RT, Heuch I, Irgens LM. A temporary increase of Down syndrome among births of young mothers in Norway: an effect of risk unrelated to maternal age? Genet Epidemiol 1991; 8: 217–230.

[30] Migliore L, Migheli F, Coppedè F. Susceptibility to aneuploidy in young mothers of Down syndrome children. Sci World J 2009; 9: 1052–1060.

[31] Kaur A, Kaur A. Role of folate metabolizing genes and homocysteine in mothers of Down syndrome children. Tzu Chi Med J 2022; 34: 456–461.