Each one of the following features is seen in phenylketonuria, except:
Correct Answer D:
Phenylketonuria:
Phenylketonuria (PKU) is an autosomal recessive condition caused by a disorder of phenylalanine metabolism.
This is due to defect in phenylalanine hydroxylase, an enzyme which converts phenylalanine to tyrosine. High levels of phenylalanine lead to problems such as learning difficulties and seizures. The gene for phenylalanine hydroxylase is located on chromosome 12. The incidence of PKU is c. 1 in 10,000 live births.
Features:
Diagnosis:
Management:
*Secondary to phenylacetate, a phenylketone
Which one of the following statements is true regarding monoclonal antibodies?
Correct Answer D: Monoclonal antibodies: Monoclonal antibodies have an increasing role in medicine. They are manufactured by a technique called somatic cell hybridization. This involves the fusion of myeloma cells with spleen cells from a mouse that has been immunized with the desired antigen. The resulting fused cells are termed a hybridoma and act as a 'factory for producing monoclonal antibodies. The main limitation to this is that mouse antibodies are immunogenic leading to the formation of human anti-mouse antibodies (HAMAs). This problem is overcome by combining the variable region from the mouse body with the constant region from an human antibody.
Clinical examples of monoclonal antibodies:
Monoclonal antibodies are also used for:
A study is designed to look at the efficacy of a mandible advancement device in reducing snoring. The severity of snoring was assessed by the partner using a 10 point scale before and after using the device. Fifty people were involved in the study.
What is the most appropriate statistical test to apply to this data?
Correct Answer C:
The data in this study is non-parametric, paired and comes from the same population. These factors make the Wilcoxon signed-rank test the most appropriate statistical hypothesis test to use.
Significance tests: types:
The type of significance test used depends on whether the data is parametric (something which can be measured, usually normally distributed) or non-parametric.
Parametric tests:
Non-parametric tests:
Paired data refers to data obtained from a single group of patients, e.g. Measurement before and after an intervention. Unpaired data comes from two different groups of patients, e.g. Comparing response to different interventions in two groups.
A 33-year-old pregnant woman presents for advice. She is known to have polycystic kidney disease but is currently well. Her father also has polycystic kidneys and is on dialysis .
What is the chance her child will also have the disease?
Correct Answer B:
Polycystic kidney disease is usually inherited in an autosomal dominant fashion and hence 50% of her children will be affected, regardless of gender. The autosomal recessive form is rare and usually causes death in childhood.
ADPKD:
Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of kidney disease, affecting 1 in 1,000 Caucasians. Two disease loci have been identified, PKD1 and PKD2, which code for polycystin-1 and polycystin-2 respectively.
The screening investigation for relatives is abdominal ultrasound:
Ultrasound diagnostic criteria (in patients with positive family history):
Which one of the following statements is true regarding interferon?
Interferon:
Interferons (IFN) are cytokines released by the body in response to viral infections and neoplasia. They are classified according to cellular origin and the type of receptor they bind to. IFN-alpha and IFN-beta bind to type 1 receptors whilst IFN-gamma binds only to type 2 receptors.
IFN-alpha:
IFN-beta:
IFN-gamma:
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