Chromosomal Abberations PDF

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FreshestYeti

Uploaded by FreshestYeti

Faculty of Physical Therapy - MSA University

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chromosomal aberrations genetic mutations medical genetics biology

Summary

This document provides a detailed overview of chromosomal aberrations. It describes different types such as deletion, duplication, inversion, and translocation. Understanding their mechanisms and consequences is crucial in medical genetics.

Full Transcript

Chromosomal abberations Definition Deviation from normal NO. Or str of chr Commonly Cause MR & developmental R strucural aberrations= mutation Inf Viral irradiation Balanced ab = Insecticides chr has normal Drugs genetic information...

Chromosomal abberations Definition Deviation from normal NO. Or str of chr Commonly Cause MR & developmental R strucural aberrations= mutation Inf Viral irradiation Balanced ab = Insecticides chr has normal Drugs genetic information unbalanced ab = chr miss genetic information strucural abberations types 1- Break Heal by reunion of sticky ends strucural abberations types 2- Deletion = Loss of fragmented part terminal interstitial ring 1 br+ loss 2 br+ from 1 end loss of sgment in between: 2 br+ loss+ reunion in a ring Wolf s= deletion of short arm of chr 4 Cri du chat s= deletion of short arm of chr 5 strucural abberations types 3-Duplication Addition of extra piece of homologous chr due to unequal crossing over → 2 copies of same gene on chr strucural abberations types 4- Inversion 2 breaks + reunion in inverted form:- Peri centric: break on both sides of centromere Para centric: break on one side strucural abberations types 5- Transfere of chr segment Translocation to non homologous chr t 14 21 a) Robersonian TL= Centric fusion: In acrocentric chr 14&21 Fusion of both long arms→ chr t Loss both short arms( insignificant) 3-4% of cases of Down s. N.B IF a parent is a carrier of chr 21 translocation The risk of having Down child is up to 100% b) Reciprocal translocation: Transfere of chr segment to non homologous chr Its balanced as no genes are lost or added If chr 22&9 = philadelphia chr Diagnostic of CML strucural abberations types 6-Isochromosomes TS division of chr during anaphase of mitosis 2 non similar chromatids 2 non similar chromsomes 1 has 2 long arms & 1 has 2 short arms In submetacentric chr

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