Genetics - First Aid USMLE Flashcards
Modes of inheritance
What mode of Inheritance is presented here?
Modes of inheritance
X-linked recessive
Inheritance Pattern of:
Wiskott-Aldrich syndrome
Inheritance Pattern
Wiskott-Aldrich syndrome - X-linked Recessive
Mneumonic: Obliviously Female Will Often Give Her Boys Her x-Linked Disorders
Genetics - First Aid 2019
Genetic terms: Example(s) for -
Loss of heterozygosity
Genetics - First Aid 2019
Example(s) for - Loss of heterozygosity
Retinoblastoma and the “two-hit hypothesis,”
Lynch syndrome (HNPCC), Li-Fraumeni
syndrome.
Genetic disorders by Chromosome
Cri-du-chat syndrome, familial adenomatous polyposis
Genetic disorders by Chromosome
Cri-du-chat syndrome, familial adenomatous polyposis
Chromosome 5
Inheritance Pattern of:
Familial Adenomatous Polyposis
Inheritance Pattern
Familial Adenomatous Polyposis- Autosomal Dominant
Inheritance Pattern of:
Ornithine transcarbamylase deficiency
Inheritance Pattern
Ornithine transcarbamylase deficiency - X-linked Recessive
Mneumonic: Obliviously Female Will Often Give Her Boys Her x-Linked Disorders
Genetics - First Aid 2019
Genetic terms: Example(s) for -
Codominance
Genetics - First Aid 2019
Example(s) for - Codominance
Blood groups A, B, AB; α1-antitrypsin
deficiency; HLA groups.
Inheritance Pattern of:
Friedreich ataxia
Inheritance Pattern
Friedreich ataxia - Autosomal Recessive
Inheritance Pattern of:
Achondroplasia
Inheritance Pattern
Achondroplasia - Autosomal Dominant
Inheritance Pattern of:
Bruton agammaglobulinemia
Inheritance Pattern
Bruton agammaglobulinemia - X-linked Recessive
Mneumonic: Obliviously Female Will Often Give Her Boys Her x-Linked Disorders
Genetic disorders by Chromosome
von Hippel-Lindau disease, renal cell carcinoma
Genetic disorders by Chromosome
von Hippel-Lindau disease, renal cell carcinoma
Chromosome 3
Inheritance Pattern of:
Ocular albinism
Inheritance Pattern
Ocular albinism - X-linked Recessive
Mneumonic: Obliviously Female Will Often Give Her Boys Her x-Linked Disorders
Modes of inheritance
Autosomal dominant: Often due to defects in ________ genes. Many generations, both males and females are affected.
Modes of inheritance
Autosomal dominant: Often due to defects in structural genes. Many generations, both males and females are affected.
Modes of inheritance
What mode of Inheritance is presented here?
Modes of inheritance
Autosomal ressecive
Inheritance Pattern of:
Li-Fraumeni syndrome
Inheritance Pattern
Li-Fraumeni syndrome - Autosomal Dominant
Genetics - First Aid 2019
Genetic terms: Definition
Locus heterogeneity
Genetics - First Aid 2019
Definition: Locus heterogeneity
Mutations at different loci can produce a similar
phenotype.
Inheritance Pattern of:
Oculocutaneous albinism
Inheritance Pattern
Oculocutaneous albinism- Autosomal Recessive
Inheritance Pattern of:
von Hippel-Lindau disease
Inheritance Pattern
von Hippel-Lindau disease - Autosomal Dominant
Genetics - First Aid 2019
Genetic terms: Definition
Pleiotropy
Genetics - First Aid 2019
Definition: Pleiotropy
One gene contributes to multiple phenotypic
effects.
Inheritance Pattern of:
Fabry disease
Inheritance Pattern
Fabry disease- X-linked Recessive
Mneumonic: Obliviously Female Will Often Give Her Boys Her x-Linked Disorders
Inheritance Pattern of:
Multiple Endocrine Neoplasias (MEN)
Inheritance Pattern
Multiple Endocrine Neoplasias (MEN) - Autosomal Dominant
Genetic disorders by Chromosome
ADPKD (PKD1), α-globin gene defects (eg, α-thalassemia), tuberous sclerosis (TSC2)
Genetic disorders by Chromosome
ADPKD (PKD1), α-globin gene defects (eg, α-thalassemia), tuberous sclerosis (TSC2)
Chromosome 16
Inheritance Pattern of:
Mucopolysaccharidoses (except Hunter syndrome)
Inheritance Pattern
Mucopolysaccharidoses - Autosomal Recessive
(except Hunter syndrome)
Genetics - First Aid 2019
Genetic terms: Example(s) for -
Variable expressivity
Genetics - First Aid 2019
Example(s) for - Variable expressivity
2 patients with neurofibromatosis type 1 (NF1) or Polydactyly may have varying disease severity.
Genetic disorders by Chromosome
Neurofibromatosis type 1, BRCA1, TP53
Genetic disorders by Chromosome
Neurofibromatosis type 1, BRCA1, TP53
Chromosome 17
Modes of inheritance
Mitochondrial inheritance: Mitochondrial myopathies
Modes of inheritance
Mitochondrial myopathies - rare disorders;
often present with myopathy, lactic acidosis,
and CNS disease, eg, MELAS syndrome
(mitochondrial encephalomyopathy, lactic
acidosis, and stroke-like episodes). 2° to
failure in oxidative phosphorylation.
Inheritance Pattern of:
Hereditary Spherocytosis
Inheritance Pattern
Hereditary Spherocytosis - Autosomal Dominant
Disorders of imprinting
Prader-Willi syndrome - Chromosome and Disomy Associated:
Disorders of imprinting
Prader-Willi syndrome - Associated with:
Associated with a mutation or deletion of chromosome 15 of paternal origin. Prader has no Papa (Paternal deletion).
25% of cases are due to maternal uniparental disomy.
Inheritance Pattern of:
hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome)
Inheritance Pattern
hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome) - Autosomal Dominant
Inheritance Pattern of:
Hemochromatosis
Inheritance Pattern
Hemochromatosis - Autosomal Recessive
Genetics - First Aid 2019
Genetic terms: Example(s) for -
Heteroplasmy
Genetics - First Aid 2019
Example(s) for - Heteroplasmy
mtDNA passed from mother to all children.
Genetics - First Aid 2019
Genetic terms: Definition
Anticipation
Genetics - First Aid 2019
Definition: Anticipation
Increased severity or earlier onset of disease in
succeeding generations.
Genetics - First Aid 2019
If a population is in _Hardy-Weinberg
equilibrium_ and if p and q are the frequencies
of separate alleles, then: p2 + 2pq + q2 = 1 and
p + q = 1, which implies that:
Genetics - First Aid 2019
Hardy-Weinberg equilibrium: The values of p and q remain constant from generation to generation.
p2 = frequency of homozygosity for allele A
q2 = frequency of homozygosity for allele a
2pq = frequency of heterozygosity (carrier
frequency, if an autosomal recessive disease).
The frequency of an X-linked recessive disease
in males = q and in females = q2.
Genetics - First Aid 2019
Genetic terms: Example(s) for -
Incomplete Penetrance
Genetics - First Aid 2019
Example(s) for - Incomplete Penetrance
BRCA1 gene mutations do not always result in
breast or ovarian cancer.
Inheritance Pattern of:
Cystic Fibrosis
Inheritance Pattern
Cystic Fibrosis - Autosomal Recessive
Inheritance Pattern of:
Marfan syndrome
Inheritance Pattern
Marfan syndrome - Autosomal Dominant
Genetics - First Aid 2019
Genetic terms: Definition
Incomplete Penetrance
Genetics - First Aid 2019
Definition: Incomplete Penetrance
Not all individuals with a mutant genotype
show the mutant phenotype.
% penetrance × probability of inheriting
genotype = risk of expressing phenotype.
Inheritance Pattern of:
PKU
Inheritance Pattern
Phenylketonuria - Autosomal Recessive
Genetics - First Aid 2019
Genetic terms: Definition
Dominant negative mutation
Genetics - First Aid 2019
Definition: Dominant negative mutation
Exerts a dominant effect. A heterozygote
produces a nonfunctional altered protein that
also prevents the normal gene product from
functioning.
Genetics - First Aid 2019
Genetic terms: Definition
Allelic heterogeneity
Genetics - First Aid 2019
Definition: Allelic heterogeneity
Different mutations in the same locus
produce the same phenotype.
Genetic disorders by Chromosome
Hemochromatosis (HFE)
Genetic disorders by Chromosome
Hemochromatosis (HFE)
Chromosome 6
Genetics - First Aid 2019
Genetic terms: Definition
X-inactivation (lyonization)
Genetics - First Aid 2019
Definition: X-inactivation (lyonization)
one copy of female X chromosome forms a
transcriptionally inactive Barr body. Female
carriers variably affected depending on the
pattern of inactivation of the X chromosome
carrying the mutant vs normal gene.