Cytogenetic DisordersCytogenetic Disorders

Numeric AbnormalitiesNumeric AbnormalitiesStructural AbnormalitiesStructural Abnormalities

Numeric AbnormalitiesNumeric Abnormalities

EuploidEuploid– DiploidDiploid– PolypoidPolypoid

AneuploidAneuploid– MonosomyMonosomy– TrisomyTrisomy

MosaicismMosaicism

Structural AbnormalitiesStructural Abnormalities

Cytogenetic Disorders Involving Cytogenetic Disorders Involving AutosomeAutosome

Trisomy 21 (Down Syndrome)Trisomy 21 (Down Syndrome)

Chromosome 22q11 Deletion Chromosome 22q11 Deletion SyndromeSyndrome

Velocardiofacial syndromeVelocardiofacial syndrome

DiGeorge syndromeDiGeorge syndrome

Fluorescence In Situ Fluorescence In Situ Hybridization (FISH)Hybridization (FISH)

Accompanied by karyotyping to increase the Accompanied by karyotyping to increase the power of cytogenetic analysispower of cytogenetic analysis

Fluorescence In Situ Fluorescence In Situ Hybridization (FISH)Hybridization (FISH)

Advantages of FISHAdvantages of FISH– Number of chromosomes in interphaseNumber of chromosomes in interphase

DNA probes that recognize chromosome-specific DNA probes that recognize chromosome-specific sequencessequences

– Subtle microdeletionsSubtle microdeletions 22q11 deletion syndrome22q11 deletion syndrome

– Complex translocationsComplex translocations

FISHFISH

Cytogenetic Disorders Involving Cytogenetic Disorders Involving Sex ChromosomesSex Chromosomes

Single-Gene Disorders with Single-Gene Disorders with Atypical Patterns of InheritanceAtypical Patterns of Inheritance

Triple Repeat MutationsTriple Repeat Mutations

Fragile X SyndromeFragile X Syndrome

CGG repeats:Normal around 29Premutation 52-230Full mutation 230-4000

Fragile X syndromeFragile X syndrome

FMR1 geneFMR1 gene FMR proteinFMR protein

– RNA-binding protein that RNA-binding protein that regulates protein regulates protein translationtranslation

Higher level of transcripts Higher level of transcripts in the brain and the testisin the brain and the testis

Leber hereditary optic Leber hereditary optic neuropathyneuropathy

Mutations in Mitochondrial Mutations in Mitochondrial GeneGene

Genomic ImprintingGenomic Imprinting

Farid A. Ardalan, MD, AP, CPFarid A. Ardalan, MD, AP, CP

azmoudeh@sina.tums.ac.irazmoudeh@sina.tums.ac.ir

IKMC:IKMC:

+98-21-919-2403+98-21-919-2403