Advanced Genetics: Mutation and Disease

In AD disorders, new mutations are mostly paternally inherited due to mutations in GERM cells of older males, rather than being maternally inherited or randomly inherited. Inheriting AD disorders equally from both parents with a 50/50 chance is not characteristic of the mode of inheritance for these disorders.

Turner's syndrome is characterized by the absence of one X chromosome in females, leading to various developmental and medical issues. Understanding the mechanisms behind its occurrence can shed light on potential genetic causes and risk factors.

Turner's syndrome is associated with normal intelligence.

The correct approach is to start with a Triple Marker screen due to its less invasive nature and initial assessment of specific biomarkers before considering invasive diagnostic testing for confirmation.

The correct answer is Nondisjunction in Maternal Meiosis 1, which leads to Down's syndrome being the most common cause of Floppy baby syndrome. Honey contaminated with botulinum toxin and Prader-Willi syndrome are not major risk factors for this syndrome. Advanced maternal age, which increases the risk of Down's syndrome and other trisomies, is the key factor to consider.

Nondisjunction leading to mosaicism occurs when chromosomes fail to separate correctly during mitosis, resulting in multiple cell lines from a single zygote. Turner syndrome is a commonly tested example where mosaicism is common due to the survival advantage. Nondisjunction during meiosis can lead to complete monosomies or trisomies, but the focus here is on mitotic non-disjunction for mosaicism.

Vitamin D resistant rickets is specifically linked to an X-linked dominant defect in phosphate reabsorption, differentiating it from the other inheritance patterns and mechanisms mentioned.

Fragile X syndrome is the correct answer as it is an X-linked dominant disorder caused by a CGG repeat on the FMR1 gene, leading to mental retardation. Down syndrome is actually the overall most common cause of mental retardation, but it is not a mendelian disorder. Turner syndrome and Klinefelter syndrome are not typically associated with mental retardation.

Marfan syndrome is known for having an INCOMPLETE penetrance, meaning that individuals can be phenotypically normal despite carrying the mutation. This is different from Familial Polyposis on Chr. 5, which has COMPLETE penetrance where all individuals with the mutation will express the phenotype.

The correct answer is that patient has 21 hydroxylase deficiency which is inherited in an autosomal recessive manner. This condition is characterized by the symptoms mentioned in the question such as hirsutism, hyperkalemia, hypotension, and increased renin levels.

B thalassemia major is characterized by mutations that result in reduced or absent production of the Bglobin chain. This leads to a decrease in HemA(a2B2) and an increase in HemA2(a2D2) and HemF(A2Y2) chains.

These genetic conditions are inherited in an autosomal recessive manner, meaning that both copies of the gene must be mutated to manifest the disease.

The correct inheritance pattern for the described condition is autosomal recessive as explained in the answer section.

This question is related to Maple Syrup urine disease, which is an autosomal recessive disorder caused by a lack of Branched chain a-ketoacid dehydrogenase. The key feature includes the sweet-smelling urine, mental retardation, and seizures due to the accumulation of Isoleucine, Leucine, and Valine. While the incorrect answers refer to different genetic inheritance patterns resulting in other metabolic disorders with distinct characteristics.

The correct answer explains that the accumulation of Fructose 1 phosphate due to Aldolase B deficiency causes cirrhosis and hypophosphatemia in patients with Hereditary fructose intolerance. Avoiding honey and sucrose helps manage the condition.

Homogentisate Oxidase deficiency leads to a decrease in Maleylacetoacetate levels, resulting in the black discolorations seen in degenerative arthritis. Alkaptonuria is an autosomal recessive condition caused by this deficiency.

GALT deficiency leads to the inability to convert galactose-1-phosphate to UDP-galactose, resulting in increased galactose-1-phosphate and decreased glucose levels. The disorder is inherited in an autosomal recessive manner, meaning that both copies of the gene must be mutated for the condition to be present.

Hereditary angioedema is caused by C1 esterase inhibitor deficiency and is inherited in an Autosomal Dominant pattern.

The correct answer is Myotonic dystrophy, as it is characterized by CTG repeat expansion on chromosome 19 leading to the mentioned symptoms.

In spermatogenesis, CAG amplification occurs in the context of Huntington's disease, while CGG amplification occurs in Oogenesis leading to Fragile X syndrome. The incorrect answers provided do not accurately reflect the specific amplification patterns observed in these processes.

Missense mutation results in a single amino acid change in the protein sequence, while frameshift mutation involves insertion or deletion of nucleotides, silent mutation does not result in amino acid change, and nonsense mutation leads to premature termination of protein synthesis.