Chromosome Disorders Classification of genetic disorders Singlegene disorders

Chromosome Disorders

Classification of genetic disorders § Single-gene disorders (2%) § Chromosome disorders (<1%) § Multifactorial disorders (60%)

Types of Mutation class of mutation mechanism frequency examples Genome chromosome 10 -2 / cell aneuploidy missegregation division Chromosome chromosome 10 -4 / cell transrearrangement division locations Gene base-pair mutation 10 -10 / cell point division mutations

Chromosome disorders üaccounting for about half of all spontaneous first-trimester abortions üaffecting about 1% liveborn infants • Chromosome Mutation • Genome Mutation

Chromosome Mutation abnormalities of chromosome structure • Unbalanced rearrangements (sick) deletions, duplications • Balanced rearrangements (healthy) inversions, translocations

Unbalanced rearrangements

Unbalanced rearrangements

Unbalanced rearrangements

Balanced rearrangements

Balanced rearrangements

Balanced rearrangements

Balanced rearrangements

Genome Mutation abnormalities of chromosome number due to nondisjunction (chance occurrence) euploid – an exact multiple of the haploid chromosome number • Aneuploidy – trisomy, monosomy • Polyploidy – triploid (3 n), tetraploid (4 n)

Down syndrome (ultrasound examination)

Down syndrome

Turner syndrome

Turner syndrome

Turner syndrome

Klinefelter syndrome

Klinefelter syndrome

Klinefelter syndrome

Literature Biology, eighth edition, Campbell, Reece Unit three: Genetics Chapter 15: The Chromosomal Basis of Inheritance Concept 15. 4: Alterations of chromosome number or structure cause some genetic disorders Pages 297 – 300