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Chromosome aberration
Dr. rer. nat. Kartika Senjarini
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Intro
Chr. Aberration: perubahan pada keadaankromosom normal dalam sel yang
menyebabkan perubahan komposisi
genetik sehingga berakibat fatal dankeabnormalan kromosom
Aneuploidi adalah salah satu abnormalitas
kromosom yang berkaitan denganpengurangan dan/atau penambahan
jumlah kromosom
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Proses
DELETION
DUPLICATION
INVERSION
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Proses
INSERTION
TRANSLOCATION
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Proses
ANEUPLOIDIKebanyakan abnormalitas kromosom akan
membawa pada cacat genetik, bahkan
bersifat lethal pada kebanyakan aneuploidiPada manusia kebanyakan aneuploid
gametes diproduksi dengan kecepatan yang
cukup tinggi ketika meioses, dan sangatsedikit dari embrio yang aneuploidi ini yang
bisa bertahan hidup
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Gambar diatas menunjukkan insiden
aneuplodi selama perkembangan manusia
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ANEUPLOIDI PADA
MANUSIA
Kebanyakan aneuploidipada manusia adalah
trisomi, hanya 0,3% yang
lahir hidup, sementara
dilaporkan 35%
mengalami aborsispontan.
DOWN SINDROME,
aneuploidi yang umum
terjadi pada manusia.Kelainannya terjadi pada
kromosom ke 21
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FREKUENSI KEMUNGKINAN SEORANG IBU MENGALAMI
KROMOSOM NON-DISJUNCTION MENINGKAT DENGAN
BERTAMBAHNYA USIA KETIKA HAMILGrafik, 2001 Nature Publishing Group Hassold, T. & Hunt, P. To err (meiotically) is
human: the genesis of human aneuploidy. Nature Reviews Genetics 2, 288.
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DOWN SYNDROME: 47, XY or XX, +21
•
Mental retardation (IQ between 25-74 ). – An average person has an IQ between 90-110 .
• This results in a number of characteristic features:
– Short stature, broad hands, stubby fingers and toes,a w ide rounded face, a large protruding t ongue
that makes speech difficult. Individuals with thissyndrome have a high incidence of respiratoryinfections, heart defects, and leukemia.
• Incidence:
– 1/750 live births.
– Mothers in their early twenties have a risk of 1/1,500 .
– Women over 35 have a risk factor of 1/70, which jumps to 1/25 for women 45 and over.
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TRISOMI KROMOSOM
KE 16
This is the mostcommonchromosomalabnormality, but thefetuses NEVER
survive past the firsttrimester
Many first trimesterfetuses are lost inthis fashion (manyare "silent "abortions).
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POLIPLOIDI, ketika kromosom memiliki ≥ 3 kopi
Normal di tumbuhan tapi jarang di hewan
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PENCEGAHAN & TREATMENT?
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PENCEGAHAN & TREATMENT?
Removing a cell for
diagnosis from a human
embryo.
The diagnosis: trisomy
21 (Down syndrome).