DEVELOPMENTAL & GENETIC DISEASE

Teratogens-Factors that cause developmental disease-3 known types

PhysicalChemicalMicrobial

Physical Teratogens

Chemical Teratogens

Microbial Teratogens• Two types:–Direct: infects mother– Indirect: infects fetus.

(TORCH syndrome)

Chromosomal Abnormalities

Structural Abnormalities

Type Symbol Nature

Translocation t Two chromosomes break, rejoin, and exchange segments

Deletion del A segment of chromosome is lost

Inversion inv Two breaks occur; the middle piece is rotated and re-joins

Fragile site fra A chromosomal site with a tendency to break

Heterochromic site h

Chromosomal region that stains differently from the rest, often of variable size in the normal population

Duplication dup Duplication of a segment of chromosome

Ring r Arises from breaks in both arms, with loss of both ends to form a ring

Karyotype Nomenclature

46,XY, t(9;22)(q34;q11)Total number of chromosomes

Sex chromosome constitution

Sex chromosome constitution Description of abnormalities

Deletions

Translocations

Numerical Abnormalities

Numerical Abnormalities of Autosomes

Numerical Abnormalities of Sex Chromosomes

Autosomal Dominant Disorders

Autosomal Recessive Disorders

Sex linked Recessive Disorders

Sex linked Dominant Disorders

Multiple triple repeats disorders

Prenatal Diagnosis