Analisa Kromosom, Tampilan Fisik dan Tingkat IQ Siswa Tersangka Sindroma Down oleh Sekolah Luar Biasa Tipe C Yayasan Pembinaan Anak Cacat Medan

Abstract

Mental retardation is the intellectual syndrome caused by dysfunction of the central nervous system. This is manifested by sub average intellectual functioning is defined as an Intelligence Quotient (IQ) of approximately 70 or below. Mental retardation is present in about 1-3% of population and only 35% is identified for specific etiology. The recognizable etiology is chromosomal abnormality found in trisomy 21 (Syndrome Down). It is the most common feature of mental retardation with the incidence of the illness around 1 :700-800 of births. The purpose of this study is to identify the chromosomal abnormalities, physical appearance and the retarded students' IQ level of the SLB YPAC Medan. This study is a cross sectional study with 99 retarded students as population. The sample of this study is 21 students with mental retardation which suits the inclusion criteria. The chromosomal abnormalities are analyzed with cytogenetic method. The physical appearance is analyzed with physical observation and the students' IQ level based on the school database range. The karyotype study for 21 samples found that of 17 subjects; 13 subjects (76,5%) was trisomy 21 Nondisjunction, i.e. {8 subjects (47, 1 %) was 47,XX,+21, 5 subjects (29,4%) was 47,XY,+21}, 1 subject (5,9%) was mos46,XY[25]/47,XY,+21[15], 1 subject (5,9%) was 46,XY, 1 subject (5,9%) was 46,XY,t(5;11)(q23q13;q25),t(5;16)(q32q34;q24) and 1 subject (5,9%) failed. Of 19 physical observation ; 13 subjects (68,4%) identified as short stature, 5 subjects (26,3%) with small stature, 11 subjects (57,9%} with microsefalus, 3 subjects (15,8%) with abnormal ICD, 7 subjects (36,8%) with abnormal IPD, 7 subjects (36,8%) with abnormal OCD, 9 subjects (47,4%) with small ears, 4 subjects (21, 1 %) with simean crease, 5 subjects (26,3%) have abnormality in palm width, 7 subjects (36,8%) with abnormality in palm height, 11 subjects (57,9%) with extra space between the big toe and the second toe, 6 subjects (31,6%) with abnormality in soles width and 11 subjects (57,9%) with abnormality in soles height. For IQ level assessment of 19 subjects is found that 10 subjects (52,6%) with moderate mental retardation (IQ : 35-49) and 9 subjects (47,4%) suffered from mild mental retardation with IQ rate 50-69. In conclusion, mental retardation with syndrome down characteristics

is generated of extra chromosome 21 (HSA21) and inducing the over- expression of HSA21 genes. In this case, the DSCR1/RCAN1 in region

critical HSA21 is affected by inhibiting the calcineurin and decrease the defosforilate of NFATc in cytoplasma. Therefore, the defects of this system lead to the occurrence of Down Syndrome

Retardasi mental (RM) adalah sindrom karena berbagai manifestasi

disfungsi system syaraf pusat yang meliputi fungsi intelektual dibawah rata- rata dengan nilai lntelegence Quotient (IQ) < 70 atau setinggi-tingginya 75.

Prevalensi retardasi mental sebesar 1-3% dari populasi, dan hanya 35% dari populasi retardasi mental yang diketahui penyebab spesifiknya antara lain kelainan kromosom. Kelainan kromosom yang diketahui antara lain trisomi 21 (sindrom Down). Sindrom Down merupakan penyebab retardasi mental yang paling umum, dengan angka kejadian 1 : 700-800 kelahiran hidup. Penelitian ini bertujuan untuk mengetahui gambaran kromosom, tampilan fisik dan tingkat IQ siswa yang di golongkan retardasi mental di SLB C YPAC Kotamadya Medan.

Jenis penelitian ini adalah deskriptif dengan pendekatan Cross- Sectional. Populasi penelitian seluruh siswa yang digolongkan retardasi

mental yang berjumlah 99 murid. Sampel penelitian siswa yang digolongkan retardasi mental yang memenuhi kriteria inklusi berjumlah 21 murid. Kelainan kromosom dianalisa dengan metode sitogenetik. Tampilan fisik diketahui dengan observasi fisik. Nilai IQ diperoleh dari data sekolah. Hasil karyotyping 17 subjek : 13 subjek (76,5%) trisomi 21 Nondisjunction {8 subjek (47,1%) 47,XX,+21, 5 subjek (29,4%) 47,XY,+21}, 1 subjek (5,9%) mos46,XY[25]/47,XY,+21[15], 1 subjek (5,9%) 46,XY, 1 subjek (5,9%) 46,XY,t(5;11)(q23q13;q25),t(5;16)(q32q34;q24) dan 1 subjek (5,9%) gagal. Hasil observasi fisik 19 subjek : 13 subjek (68,4%) berperawakan pendek, 5 subjek (26,3%) berperawakan kurus, 11 subjek (57,9%) mempunyai mikrosefalus, 3 subjek (15,8%) memiliki ICD tidak normal, 7 subjek (36,8%) memiliki IPD tidak normal, 7 subjek (36,8%) memiliki OCD tidak normal, 9 subjek (47,4%) memiliki telinga kecil, 4 subjek (21,1%) memiliki simean crease, 5 subjek (26,3%) memiliki lebar telapak tangan tidak normal, 7 subjek (36,8%) memiliki panjang telapak tangan tidak normal, 11 subjek (57,9%) memiliki celah antara jari pertama dan kedua kaki, 6 subjek (31,6%) memiliki lebar telapak kaki tidak normal dan 11 subjek (57,9%) memiliki panjang telapak kaki tidak normal. Tingkat IQ 19 subjek : 10 subjek (52,6%) termasuk kategori retardasi mental sedang (IQ : 35-49) dan 9 subjek (47,4%) termasuk kategori retardasi mental ringan (IQ: 50-69). Retardasi mental dan karakteristik sindrom Down terjadi karena kelebihan satu kromosom 21 (HC21) yang menyebabkan over-expression gen-gen HSA21. DSCR1/RCAN1 adalah gen yang terdapat pada region critical HSA21 yang bertanggung jawab terhadap terjadinya sindrom Down. DSCR1/RCAN1 menghambat calcineurin dan menurunkan jumlah NFATc terdefosforilasi disitoplasma yang berperan penting dalam mengatur perkembangan dan organogenesis, termasuk system syaraf pusat