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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).