CHAPTER 6 – GENETIC DEVELOPMENTAL DISORDERS
Genetic System Components
v Deoxyribonucleic acid (DNA)
v Ribonucleic acid (RNA)
v Genes
v Chromosomes
Genetic Code #1
v Genes on specific chromosome locations provide information for the
production of proteins.
v Sequence of 3 DNA nitrogenous bases forms a codon, transcribed and
translated by RNA to produce a single amino acid
Chromosomes
v Double-stranded DNA in cell nucleus
o 22 pairs of autosomes
o 1 pair of sex chromosomes
v Contain genetic information of an individual
Genetic Replication #1
v Mitotic cell division
o Somatic cell division resulting in two identical daughter cells.
o Each cell contains 23 pairs of chromosomes (diploid).
v Meiotic cell division
o Gamete sex cell division (ovum, sperm).
o Each cell contains 23 single chromosomes (haploid).
,Trait Inheritance
v Genotype
v Phenotype
Genetic Mutations
v Deletion
v Duplication
v Inversion
v Insertion
v Translocation
Single Gene Trait Inheritance
v Mendelian pattern of predictable trait transmission
v Chromosome alleles
o Homozygous
o Heterozygous
v Allele expression
o Dominant
o Recessive
Genetic Inheritance Patterns #1
v Autosomal dominant
v Autosomal recessive
v Sex-linked dominant
v Sex-linked recessive
, v Mitochondrial gene disorders
Genetic Inheritance Patterns #2
v Autosomal dominant
o Mutation located on the autosome
o Inheritance of a mutation involving one dominant allele results in
expression of the trait
Genetic Inheritance Patterns #3
v Autosomal recessive
o Mutation located on the autosome.
o Inheritance of a mutation involving two recessive alleles results in
expression of the trait.
o Inheritance of a mutation involving one recessive allele results in
carrier status for the trait.
Genetic Inheritance Patterns #4
v Sex-linked
o Mutation located on the sex chromosomes
o Gender difference in inheritance
§ Most are linked to the X chromosome.
§ Males are more likely to be affected.
Genetic Inheritance Patterns #5
v Mitochondrial gene disorders
o Related to energy production
o Matrilineal inheritance
, o Not passed on by men
o Heteroplasmy
Inheritance of Polygenic Disorders
v Multiple alleles at different chromosome locations affect phenotype
v Complex interaction of multiple factors
v Environmental influences (height)
v Less predictable pattern
v Monosomy (Turner syndrome)
v Trisomy (Down syndrome)
Chromosomal Alterations #1
v Detected by karyotype
Chromosomal Alterations #2
v Alteration in chromosome number
o Nondisjunction
§ Mosaicism
§ Monosomy
§ Trisomy
Chromosomal Alterations #3
v Alteration in chromosome structure
o Translocation
Epigenetic Inheritance
v Environmental and metabolic agents
, v Histone acetylation
v DNA methylation
v Genomic imprinting
Developmental Disorders #1
v Congenital disorders
o Environmental factors (chemicals, hormones)
o Organogenesis (development of organs)
o Teratogens (e.g., fetal alcohol syndrome)
o Maternal infection (TORCH)
o Ionizing radiation
o Maternal nutrition
Management of Genetic and Developmental Disorders
v Screening and diagnosis
o Prenatal screening and diagnosis
o Postnatal screening and diagnosis
v Treatment strategies
o Assess literacy level
o Provide information about rates of risk
o Promote ability to make informed decisions
Application of Concepts of Genetics/Developmental Disorders
v Huntington disease
v Sickle cell disease
Genetic System Components
v Deoxyribonucleic acid (DNA)
v Ribonucleic acid (RNA)
v Genes
v Chromosomes
Genetic Code #1
v Genes on specific chromosome locations provide information for the
production of proteins.
v Sequence of 3 DNA nitrogenous bases forms a codon, transcribed and
translated by RNA to produce a single amino acid
Chromosomes
v Double-stranded DNA in cell nucleus
o 22 pairs of autosomes
o 1 pair of sex chromosomes
v Contain genetic information of an individual
Genetic Replication #1
v Mitotic cell division
o Somatic cell division resulting in two identical daughter cells.
o Each cell contains 23 pairs of chromosomes (diploid).
v Meiotic cell division
o Gamete sex cell division (ovum, sperm).
o Each cell contains 23 single chromosomes (haploid).
,Trait Inheritance
v Genotype
v Phenotype
Genetic Mutations
v Deletion
v Duplication
v Inversion
v Insertion
v Translocation
Single Gene Trait Inheritance
v Mendelian pattern of predictable trait transmission
v Chromosome alleles
o Homozygous
o Heterozygous
v Allele expression
o Dominant
o Recessive
Genetic Inheritance Patterns #1
v Autosomal dominant
v Autosomal recessive
v Sex-linked dominant
v Sex-linked recessive
, v Mitochondrial gene disorders
Genetic Inheritance Patterns #2
v Autosomal dominant
o Mutation located on the autosome
o Inheritance of a mutation involving one dominant allele results in
expression of the trait
Genetic Inheritance Patterns #3
v Autosomal recessive
o Mutation located on the autosome.
o Inheritance of a mutation involving two recessive alleles results in
expression of the trait.
o Inheritance of a mutation involving one recessive allele results in
carrier status for the trait.
Genetic Inheritance Patterns #4
v Sex-linked
o Mutation located on the sex chromosomes
o Gender difference in inheritance
§ Most are linked to the X chromosome.
§ Males are more likely to be affected.
Genetic Inheritance Patterns #5
v Mitochondrial gene disorders
o Related to energy production
o Matrilineal inheritance
, o Not passed on by men
o Heteroplasmy
Inheritance of Polygenic Disorders
v Multiple alleles at different chromosome locations affect phenotype
v Complex interaction of multiple factors
v Environmental influences (height)
v Less predictable pattern
v Monosomy (Turner syndrome)
v Trisomy (Down syndrome)
Chromosomal Alterations #1
v Detected by karyotype
Chromosomal Alterations #2
v Alteration in chromosome number
o Nondisjunction
§ Mosaicism
§ Monosomy
§ Trisomy
Chromosomal Alterations #3
v Alteration in chromosome structure
o Translocation
Epigenetic Inheritance
v Environmental and metabolic agents
, v Histone acetylation
v DNA methylation
v Genomic imprinting
Developmental Disorders #1
v Congenital disorders
o Environmental factors (chemicals, hormones)
o Organogenesis (development of organs)
o Teratogens (e.g., fetal alcohol syndrome)
o Maternal infection (TORCH)
o Ionizing radiation
o Maternal nutrition
Management of Genetic and Developmental Disorders
v Screening and diagnosis
o Prenatal screening and diagnosis
o Postnatal screening and diagnosis
v Treatment strategies
o Assess literacy level
o Provide information about rates of risk
o Promote ability to make informed decisions
Application of Concepts of Genetics/Developmental Disorders
v Huntington disease
v Sickle cell disease
