Anticipation in genetics refers to an increase in severity and decrease in age of onset in successive generations, most likely due to increased size of trinucleotide repeats. Paternal anticipation: Huntington’s disease, Friedreich’s Ataxia Maternal anticipation: Myotonic dystrophy, Fragile X syndrome Diseases Trinucleotide Repeat Affected gene Chromosome Fragile X syndrome CGG…
Tag: Biochemistry
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Solving Pedigree Analysis in 3 steps
First: Look for Mitochondrial Inheritance Female transmits disease to all the offsprings (both males and females). Male doesn’t transmit the disease and only the females transmit the disease. If Mitochondrial inheritance is absent, go to second step. Second: Look if the gene is Dominant, Recessive Dominant: Atleast one member in…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Lysosomal Storage Disorders Made Easy
Among the common lysosomal storage disorders: Two of them are Mucopolysaccharidoses (Hunter and Hurler syndrome) Pompe’s disease is Glycogen Storage Disease. Others are Sphingolipidoses. Inheritance of Lysosomal Storage Diseases All are inherited as Autosomal Recessive (AR) condition except: Hunter syndrome (X-linked recessive) Fabry’s disease (X-linked recessive) Higher risk in Ashkenazi…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Glucose 6 Phosphate : Central to Glucose Metabolism
Glucose-6-Phosphate central to the 4 major metabolic pathways of glucose, i.e. glycolysis, gluconeogenesis, glycogenesis, glycogenolysis and HMP shunt (Pentose phosphate pathway). Glucose is immediately phosphorylated inside the cells to Glucose-6-Phsophate to trap them inside cell and prevent diffusion out of the cell. Glucose-6-Phosphate is the key intermediate to understand the…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Glycogen Storage Diseases with Mnemonics
Once again, I’m back with a biochemistry topic that everyone hates. Let’s try to break the topic, simplify it and cover all the important aspects of Glycogen Storage Diseases (GSD). 7 types of Glycogen Storage Diseases Mnemonic:VP CAM HT. This is a pretty lame mnemonic for the order of the…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
M-spike
Synonyms: Monoclonal spike, M-protein spike, Monoclonal band, Monoclonal gammopathy Tests showing M-spike Serum Protein Electrophoresis (SPEP) Urine Protein Electrophoresis (UPEP) Normal SPEP or UPEP Electrophoresis is a method of separating proteins based on their physical properties. Albumin – the largest peak, lies closest to the positive electrode and the next five…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
VOMIT Pathway – Propionyl CoA Intermediate
Propionyl CoA is a common intermediate in catabolism of essential amino acids and odd chain fatty acids. It is also called VOMIT pathway which stands for: Valine Odd chain fatty acids Methionine Isoleucine Threonine They enter TCA cycle – using PMS pathway: Propionyl CoA Methylmalonyl CoA Succinyl CoA Defects in…
PGMEE, MRCS, USMLE, MBBS, MD/MS 
Heme Synthesis and Defects Simplified
Structure of Heme Heme is a ferro-proto-porphyrin. Heme = Protoporphyrin IX ring + Iron (Fe) in center Protoporphyrin IX = porphyrin with attachment to 4 Methyl, 2 Propionyl and 2 Vinyl groups. Porphyrin = Cyclic structure with 4 pyrrole rings Pyrrole rings are derived from Porphobilinogen (PBG) Hydroxymethylbilane = Linear…