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Topic Index - Medical Genetics

Medical Genetics Home

Overview of Birth Defects

Chromosome Abnormalities


Overview of Chromosome Abnormalities

Types of Chromosome Abnormalities

Numerical Abnormalities: Overview of Trisomies and Monosomies

Down Syndrome (Trisomy 21)

Trisomy 18 & 13

Turner Syndrome

Structural Abnormalities: Deletions (Cri du Chat) and Duplications (Pallister Killian)


Translocation Down Syndrome


Mosaic Down Syndrome

How Chromosome Abnormalities Happen: Meiosis, Mitosis, Maternal Age, Environment

Chance a Chromosome Abnormality Will Occur Again: Numerical, Structural (Inherited and De Novo), Mosaicism

Single Gene Defects

Autosomal Recessive: Cystic Fibrosis, Sickle Cell Anemia, Tay Sachs Disease

X-linked Recessive: Red-Green Color Blindness, Hemophilia A

X-linked Dominant: Incontinentia Pigmenti

Multifactorial Inheritance


Teratogens Overview

Examples of Teratogens

Fetal Alcohol Syndrome (FAS)

Phenytoin (Dilantin)


Non-Traditional Inheritance

Uniparental Disomy: Prader-Willi Syndrome, Angelman Syndrome

Trinucleotide Repeats: Fragile-X Syndrome

Mitochondrial Inheritance: Leber's Optic Atrophy

Evaluating a Child for Birth Defects

Medical History and Genetic Testing

Testing for Birth Defects

Chromosome Studies: Karyotype, Extended Banding, Fluorescence In Situ Hybridization (FISH), and Chromosomal Microarray Analysis

Studies for Single Gene Defects: DNA (Direct and Indirect)

Biochemical Genetic Testing

Uses of Genetic Testing

Genetic Services: When, Where, How

Identification, Treatment, and Prevention of Birth Defects

The Human Genome Project

Vitamin, Gene, and Enzyme Replacement Therapy

Before Your Next Pregnancy

When to Seek Genetic Counseling

Support Groups