Gene expression disorders / Questions and case reports

Questions

 * 1) Translation of 2200 bp mRNA results in a product the size of:
 * 2) * A – 1100 bp
 * 3) * B - 494 amino acid residues
 * 4) * C – 196 kDa
 * 5) * D - 985 amino acid residues
 * 6) Tissue-specific mRNA editing is provided mainly by:
 * 7) * A - mitochondrial specific tRNAs
 * 8) * B - eRNA
 * 9) * C - gRNA
 * 10) * D - ribosomal RNA (rRNA)
 * 11) A frameshift mutation does not usually lead to this change:
 * 12) * A - New cap creation or the placement of the cap in a new place
 * 13) * B - Elongated protein
 * 14) * C - Altered biological half-life of the protein
 * 15) * D - New stop codon creation
 * 16) Which answer is incorrect? Nuclear gene expression is regulated:
 * 17) * A - By transcription factors
 * 18) * B - In the promoter region
 * 19) * C - Using nuclear receptors
 * 20) * D - Via negative feedback according to the amount of mRNA in mitochondria

Newborn with focal seizures
The patient, 4 days old, was left in the neonatal unit for focal seizures. Biochemical examination was repeatedly normal. Epileptic activity was detected by EEG. The pediatric neurologist evaluated the finding as benign focal neonatal epilepsy. Extensive family history has shown a frequent occurrence of epilepsy in the family. The patient was diagnosed with a 283insGT mutation in KCNQ2.

Questions:


 * 1) What biochemical tests have been performed?
 * 2) What is the biochemical basis of hereditary epilepsy?
 * 3) What does 283insGT stand for and what does such a mutation lead to?

Patient with hypertension and the metabolic disorder
The patient, 4 years old, was admitted to the pediatric ward because he lost consciousness. The examination revealed hypotension, S-K level of 2.6 mmol/L, 7.8 pH, and HCO3 level of 52 mmol/L. The Nordin index was 1.4. The P124L mutation in CLC-Kb was detected. Questions:


 * 1) What disease could it be? And what would be the laboratory findings necessary to confirm the diagnosis?
 * 2) What is the Nordin Index?
 * 3) What is the cause of this syndrome?
 * 4) What is CLC-Kb and what does the abbreviation P124L mean?

A patient with colorectal cancer
A patient, 52 years old, was examined on an outpatient basis for fatigue, subfebrile illness, gastrointestinal problems, and recurrence of fresh blood and sometimes mucus in the stool. A biopsy was performed from a suspected tumor site during rectoscopy. The biopsy sample was examined histologically (adenocarcinoma) and molecular genetically for the presence of mutations in the K-ras gene (substitution at position 2 of codon 12, GGT → GCT).

Questions:


 * 1) What other laboratory tests would be appropriate to monitor the patient?
 * 2) What is the K-ras gene and what is its significance?
 * 3) What is the consequence of this point mutation?

A patient with liver cirrhosis
A patient, 55 years old, visited her family doctor for persistent weakness, lethargy, loss of libido, and joint pain. She was diagnosed with diabetes mellitus six months ago. Hepatomegaly and hyperpigmentation of the skin were found on physical examination. There were signs of cardiomyopathy on the ECG. Biochemical examinations and liver biopsies were performed. DNA was isolated from peripheral leukocytes and examined for the presence of the C282Y mutation in the HLA-H (HFE) gene.

Questions:


 * 1) What biochemical tests should be performed? What histological examination was performed on the biopsy specimen?
 * 2) What disease is it and how is it treated?
 * 3) What is the cause of this disease?
 * 4) What does C282Y stand for?

Related articles

 * Gene expression
 * Control of gene expression and proteosynthesis in eukaryotes
 * Transcription
 * Translation

Source

 * MASOPUST, Jaroslav and Richard PRŮŠA. Pathobiochemistry of metabolic pathways. 1st edition. Prague: Charles University, 1999. 182 pp. 214–218.  ISBN 80-238-4589-6.

Catgeory: Pathobiochemistry