Essentials of Medical Genetics Quiz

The correct answer is 5%, as approximately 1 in every 20 children are born with a congenital abnormality.

Genetic disorders can be caused by various factors such as single-gene defects, mitochondrial disorders, chromosomal imbalances, or a combination of genetic and environmental factors. Acquired genetic mutations, autoimmune disorders, and metabolic disorders are not classified as types of genetic disorders.

Genetic disorders can be classified into different types, with autosomal and X-linked being two of the most common categories. Mitochondrial disorders involve mutations in the DNA of mitochondria, chromosomal disorders result from abnormalities in chromosomes, and polygenic disorders are influenced by multiple genes.

Autosomal recessive mutations are typically caused by loss of function mutations where there is a disruption in the gene product leading to a non-functional or reduced functional protein. Insertions, deletions, premature stop codons, and frame shift mutations are common types of mutations that can result in autosomal recessive disorders.

The correct answer is chromosome 7 where the cystic fibrosis gene is located. It is important to know the specific chromosome to understand the genetic basis of the condition.

The cystic fibrosis gene normally produces the protein known as the cystic fibrosis transmembrane conductance regulator, which plays a key role in regulating the flow of salt and fluids in and out of cells.

Cystic Fibrosis is most commonly caused by the deletion of 3 nucleotides from the gene, resulting in the loss of phenylalanine. Other genetic defects such as insertion of an additional nucleotide, substitution leading to a stop codon, or deletion of a different number of nucleotides do not result in the same condition.

The correct location for the phenylalanine amino acid in CF is Delta F508 on the long arm of chromosome 7.

The normal role of CFTR is specific to regulating the passage of chloride ions through specialized endothelial cells, leading to an imbalance in salt and water. The incorrect answers provided relate to functions that are not associated with CFTR.

The prevalence rate of CF is approximately 1 in 2000 live births. This genetic disorder affects the respiratory and digestive systems, leading to chronic lung infections and difficulty in absorbing nutrients.

Consanguinity is the term used to describe individuals who are closely related by blood. When partners share a common ancestor in the recent past, there is a risk of passing down recessive alleles to offspring, increasing the chances of genetic disorders. This risk is highest in relationships like siblings or parent and child.

When an individual inherits one recessive allele from each parent, the probability of inheriting a recessive allele is 1/2 or 0.5, as there are two possible outcomes - inheriting the recessive allele or not inheriting it.

The correct answer is based on the principle of Mendelian genetics stating that each parent pass on one allele for each gene, resulting in a 50% chance (or 1/2 probability) of inheriting a certain allele from each relative. Multiplying the probabilities for each descendent provides the overall probability of inheriting a specific allele from multiple relatives.

The correct formula to calculate the inbreeding coefficient is 4 * (1/2)^n, where n represents the number of generations between the two individuals. This formula helps determine the level of consanguinity or genetic relatedness between individuals in a family tree.

Inbreeding coefficient of 1/4 is correct for offspring of sibling parents. Half siblings would result in 1/8, uncle to niece in 1/8, cousins in 1/16, and 2nd cousins in 1/32.

Autosomal dominant disorders occur when a single copy of an altered gene is enough to cause the condition. This is in contrast to recessive disorders where both copies of a gene must be altered. The incorrect answers provide misconceptions about autosomal dominant inheritance patterns.

While Alzheimer's disease, Cystic fibrosis, and Huntington's disease all have genetic components, they are typically inherited rather than caused by new mutations.

Penetrance refers to the percentage or proportion of individuals carrying a specific allele who exhibit the related phenotype. It is not related to independent segregation of alleles, presence of multiple alleles, or changing of allele dominance.

Retinoblastoma is an autosomal dominant disease with an overall 90% penetrance rate amongst carriers.

Huntington's disease is a genetic disorder that demonstrates age-dependent penetrance, meaning the symptoms and severity of the disease may not manifest until later in life. In contrast, cystic fibrosis, Marfan syndrome, and sickle cell anemia do not exhibit age-dependent penetrance as their symptoms typically present earlier in life.

The Huntington's gene is located on Chromosome 4. Mutations in this gene are responsible for Huntington's disease.

Huntington's disease is caused by trinucleotide CAG repeats in the huntingtin gene. The number of CAG repeats influences the age of onset of the disease.

The correct answer provides the appropriate ranges for each category based on CAG repeats. The incorrect answers offer ranges outside of the established thresholds for normal, inconclusive, and disease conditions.

The DNA codon CAG codes for the amino acid Glutamine. This codon is an important part of the genetic code that determines the sequence of amino acids in a protein.

In genetics, the location of a gene on a chromosome is often referred to as being on the short arm or long arm of the chromosome. In this case, the correct answer is short arm.

Anticipation in genetics is a phenomenon where certain genetic diseases worsen or show earlier onset in subsequent generations. It is not about sudden appearance of mutations or predicting outcomes based solely on family history. It is also not about the simple passage of genetic disorders unchanged from one generation to the next.