Clinical Genetics Flashcards
What are categories of genetic disorders?
Single gene disorder ( Mendelian inheritance)
Chromosomal disorder
Multifactorial
Genetic causes of diseases
Down’s syndrome
Cystic fibrosis
Huntington’s disease
Haemophilia
Multifactorial causes of disease
Spina bifida
Cleft palate
Diabetes
Schizophrenia
Environmental causes of disease
Poor diet
Infection
Accidents
Drugs
Clinical effects of cytogenetic abnormalities
Congenital abnormalities
Delayed development
Dysmorphic features
Small stature, microcephaly, failure to thrive
In adults - infertility still births miscarriage
What is vertical transmission?
Vertical transmission: Passage of a disease-causing agent (pathogen) from mother to baby during the period immediately before and after birth.
What is penetrance?
the extent to which a particular gene or set of genes is expressed in the phenotypes of individuals carrying it, measured by the proportion of carriers showing the characteristic phenotype.
Example of autosomal dominant conditions
Adult polycystic kidney disease Familial hypercholesterolaemia Marfan syndrome Huntington disease Familial breast and ovarian cancer
Examples of AR conditions
CF phenylketonuria Haemochromatosis Spinal muscular atrophy Non syndromic sensors neural deafness
What is phenylketonuria
inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine. Untreated, PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders. It may also result in a musty smell and lighter skin
Examples of X linked recessive conditions
Duchenne and Becker muscular dystrophy
Fragile x syndrome
Retinitis pigmentosa
Ocular albinism
Examples of non Mendelian inheritance
Multifactorial
Imprinting
Mitochondrial inheritance
Mosaicism
Neural tube defect is an example of what type of inheritance
Multifactorial inheritance
What environmental factors contribute to neural tube defects
Folic acid
Maternal diabetes
Explain mitochondrial disorders
Exclusively maternally inherited disease from those present in the cytoplasm of the ovum
Contains own circular 16.5Kb chromosome
Examples of mitochondrial disorders
Mitochondrial encephalopathy lactic acidosis stroke like episodes
Myoclonic epilepsy ragged red fibres
Mitochondrially inherited DM and deafness
Leber’s hereditary optic atrophy
What is genomic imprinting?
Genomic imprinting, process wherein a gene is differentially expressed depending on whether it has been inherited from the mother or from the father
What are Prader-Willi and anglemans caused by
Cytogenic deletions of the same region of chromosome 15q or by uni parental display of chromosome 15
What is the presentation of prader willi syndrome?
Neonatal hypotonia and poor feeding
Moderate mental retardation
Hyperphagia and obesity
Small genitalia
What cause prader willi syndrome
Deletion in the paternally inherited chromosome 15 or maternal uniparental disomy
What is the presentation of Angelman’s syndrome?
Happy puppet - unprovoked laughing clapping Microcephally Mental retardation Seizures Ataxia Broad based gait
What causing angelman’s syndrome?
Caused by a deletion in the maternally inherited chromosome 15 or paternal uniparental disomy
