Polimorfisme Gen Apolipoprotein E Pada Penderita Sindrom Down Trisomi 21

Malinda Meinapuri

Abstract

Abstrak
Latar Belakang: Sindrom Down merupakan suatu kelainan kromosom yang ditandai dengan adanya baik seluruhnya (trisomi 21) maupun sebagian (translokasi) suatu salinan tambahan kromosom ke 21. Apolipoprotein E (APOE) merupakan suatu bentuk protein polimorfik yang disandikan oleh suatu gen yang berlokasi pada lengan panjang kromosom 19 pada posisi 13.2 (19q13.2). Polimorfism gen APOE berkaitan dengan meningkatnya frekuensi alel ε4 yang berakibat terjadinya hambatan dalam percabangan dan pertumbuhan neuron. Dimungkinkan, penderita Sindrom Down Trisomi 21 memiliki gen APOE yang berbeda dengan kontrol sebagai faktor yang dapat mengakibatkan penuaan dini otak. Metode : Penelitian ini merupakan penelitian kasus kontrol untuk mengamati perbedaan distribusi dan frekuensi alel dan genotip gen APOE pada penderita Sindrom Down trisomi 21 dibandingkan dengan kontrol. Kasus Sindrom Down dan kontrol diambil dari data sekunder yang tersimpan di Center for Biomedical Research (CEBIOR) Semarang Indonesia. Ekstraksi DNA dilakukan dengan menggunakan metode yang terdapat di (CEBIOR) Semarang Indonesia. Kegiatan selanjutnya adalah pemeriksaan polimorfisme gen Apolipoprotein E dengan mengunakan teknik PCR dan RFLP. Hasil : Sebanyak 33 sampel dari penderita Sindrom Down, 18 laki-laki dan 15 perempuan dan 33 sampel kontrol, 18 laki-laki dan 15 perempuan. Baik sampel Sindrom Down maupun kontrol memiliki frekuensi alel ε3 paling tinggi dibandingkan dengan alel ε2 dan ε4. Pada Sindrom Down didapatkan alel ε4 4 sampel (6,1%) dan alel ε2 8 sampel (12,1%). Baik sampel Sindrom Down maupun kontrol memiliki genotip ε3/ε3 paling tinggi dibandingkan dengan genotip gen APOE lainnya. Pada Sindrom Down didapatkan genotip ε2/ε4 4 sampel (12,1%) dan genotip ε2/ε2 2 sampel (6,1%). Simpulan : Terdapat perbedaan distribusi alel dan genotip gen APOE pada penderita Sindrom Down trisomi 21 dibandingkan dengan kelompok kontrol. Diperlukan analisis sampel yang lebih banyak untuk mengkonfirmasi hasil penelitian ini.
Kata kunci: Sindrom Down, Polimorfisme, Apolipoprotein E.
Abstract
Backgrounds :Down syndrome is an abnormal chromosomal condition, characterized by the presence of all (trisomy 21) or part (such as due to translocations) of a third copy of chromosome 21. Apolipoprotein E (APOE) is a polymorphic protein coded by a gene located on the long arm (q) of chromosome 19, positioning at 13.2 (19q13.2). Polymorphism of APOE gene is related with the increasing of allele ε4’s frequency thus cause obstruction in neuron ramification and development. In previous study, Down Syndrome groups are having different type of APOE gene compared with control. That why it can be considered as one of the caused premature aging of brain. Methods : This is a case control study to observe the difference of distribution and frequency of APOE gene allele and genotype in Down Syndrome Trysomi 21 compared to control. Down Syndrome and control samples was taken as secondary data from Center for Biomedical Research (CEBIOR) Semarang Indonesia. DNA extraction was done by using the commonly used salting out method in CEBIOR Semarang Indonesia. Subsequently polimorphism of APOE gene analysis has been done by using PCR and RFLP.Result : Thirty three samples were Down Syndrom patients, consist of 18 male and 15 female. Thirty three samples are control, consist of 18 male and 15 female. Both groups were having the highest frequency of allele ε3 compared to allele ε2 and ε4. In Down Syndrome, frequency of ε4 allele was found in 4 samples (6,1%) while allele ε2 was found in 8 samples (12,1%). Genotype ε3/ε3 were the highest frequency on both group compared to the other. In Down Syndrome group identified ε2/ε4 genotype in 4 samples (12,1%) and ε2/ε2 genotype in 2 samples (6,1%).Conclusion : There is slight difference distribution of APOE gene allele and genotype in Down Syndrome Trysomi 21 compared to control. More samples should be analyzed to confirm this finding.
Keywords:Down Syndrome, Polymorpism, Apolipoprotein E.

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