Posted in General pathology, pathology

Types of severe combined immunodeficiency disease (SCID)

SCID or severe combined immunodeficiency disease is one of the most widely studied immunodeficiency diseases. Two types of severe combined immunodeficiency disease (SCID) exist with different modes of inheritance and gens involved.

Differences between the two are discussed below.

X- LINKED SCID

It is the commonest form of SCID accounting for 50-60%

Since inheritance is X-linked, it is more common in boys.

Defect is caused due to mutation in the common gamma chain subunit of cytokine receptors.

Defect in T cells are more pronounced compared to B cells. Defects in NK cell is also present

Thymus is small and devoid of lymphoid follicles and contains lobules of undifferentiated epithelial cells resembling fetal thymus.

Gene therapy has been successful.

AUTOSOMAL RECESSIVE SCID

Most common form of AR SCID
Defect in T> B cells

Thymus is small and devoid of lymphoid follicles and remnants of Hassall’s corpuscles can be found.

Hematopoietic stem cell transplantation is the mainstay of treatment. Enzyme therapy and gene therapies have been tried.

SOME OTHER FORMS OF AUTOSOMAL RECESSIVE SCID

Mutations in recombinase-activating genes (RAG)

Mutations in JAK 3 have similar effects as mutations in the γc chain.

Several mutations have been described in signaling molecules associated with the T-cell antigen receptor and components of calcium channels.

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Posted in General pathology

Robbins pathologic basis of disease 10th edition updates

Robbins pathologic basis of disease 10th edition has a handful of changes and updates when compared to it’s predecessor.

Here is a brief note on the chapterwise general pathology updates which are high yield for entrance exams.

ROBBINS 10TH EDITION CHAPTERWISE UPDATES

CHAPTER 1- CELL

  • Satellite DNA– A major component of centromeres is so-called satellite DNA, consisting of large arrays—up to megabases in length—of repeating sequences (from 5 bp up to 5 kb). Although classically associated with spindle apparatus attachment, satellite DNA is also important in maintaining the dense, tightly packed organization of heterochromatin.
  • Gene Editing and CRISPR- An exciting new development that allows high-fidelity genome editing may usher in the next era of the molecular revolution. This advance comes from a wholly unexpected source: the discovery of clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated genes (Cas), such as the Cas9 nuclease.
Robbins pathologic basis of disease 10th edition has a handful of changes and updates when compared to it's predecessor. Here is a brief note on the chapterwise updates which are high yield for entrance exams. **ROBBINS 10TH EDITION CHAPTERWISE UPDATES** **CHAPTER 1- CELL** * ***Satellite DNA****- A major component of centromeres is so-called satellite DNA, consisting of large arrays—up to megabases in length—of repeating sequences (from 5 bp up to 5 kb). Although classically associated with spindle apparatus attachment, satellite DNA is also important in maintaining the dense, tightly packed organization of heterochromatin. * * ***Gene Editing and CRISPR- ****An exciting new development that allows high-fidelity genome editing may usher in the next era of the molecular revolution. This advance comes from a wholly unexpected source: the discovery of clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated genes (Cas), such as the Cas9 nuclease.* **CHAPTER 2- ADAPTATIONS AND INJURY** * ***Ferroptosis- ****Only discovered in 2012, ferroptosis is a distinct form of cell death that is triggered when excessive intracellular levels of iron or reactive oxygen species overwhelm the glutathione-dependent antioxidant defenses. * **CHAPTER 3-INFLAMMATION AND REPAIR** * ***Neutrophil extracellular traps (NETs)- ****NETs were mentioned in the previous edition it is further elaborated in the latest edition. Neutrophil extracellular traps (NETs) are extracellular fibrillar networks that concentrate antimicrobial substances at sites of infection and trap microbes, helping to prevent their spread.* **CHAPTER 6- IMMUNITY** * ***Rejection of tissue transplants:*** *Elaborated compared to the previous edition*. **CHAPTER 7- NEOPLASIA** * ***A few newly added proto-oncogenes: *** 1. FMS-like tyrosine kinase 3 (FLT3) Point mutation or small duplications in Leukemia. 2. GTP-binding (G) proteins- GNAQ Point mutation in Uveal melanoma. 3. GTP-binding (G) proteins- GNAS Point mutation in Pituitary adenoma. * ***A few newly added tumor suppessor genes:*** 1. SDHB, SDHD (Succinate dehydrogenase complex subunits B and D TCA cycle, oxidative phosphorylation) seen in Familial paraganglioma, familial pheochromocytoma. * ***Elaboration of oncogenic activities of E6 an E7 proteins of human papilloma virus (HPV)*** 1. In the older edition it was mentioned that the E6 protein of HPV inactivates p53. In the 10th edition it is mentioned that in addition to inactivation of p53, E6 protein also increases telomerase expression (TERT). **CHAPTER 8- INFECTIOUS DISEASES** * *Updates on the SARSCoV2 virus*
Crispr/ cas9 system update Robbins 10 th edition

CHAPTER 2- ADAPTATIONS AND INJURY

  • Ferroptosis- Only discovered in 2012, ferroptosis is a distinct form of cell death that is triggered when excessive intracellular levels of iron or reactive oxygen species overwhelm the glutathione-dependent antioxidant defenses.

CHAPTER 3-INFLAMMATION AND REPAIR

  • Neutrophil extracellular traps (NETs)NETs were mentioned in the previous edition it is further elaborated in the latest edition. Neutrophil extracellular traps (NETs) are extracellular fibrillar networks that concentrate antimicrobial substances at sites of infection and trap microbes, helping to prevent their spread.

CHAPTER 6- IMMUNITY

  • Rejection of tissue transplants: Elaborated compared to the previous edition.

CHAPTER 7- NEOPLASIA

  • A few newly added proto-oncogenes:
  1. FMS-like tyrosine kinase 3 (FLT3) Point mutation or small duplications in Leukemia.
  2. GTP-binding (G) proteins- GNAQ Point mutation in Uveal melanoma.
  3. GTP-binding (G) proteins- GNAS Point mutation in Pituitary adenoma.
  • A few newly added tumor suppessor genes:
  1. SDHB, SDHD (Succinate dehydrogenase complex subunits B and D TCA cycle, oxidative phosphorylation) seen in Familial paraganglioma, familial pheochromocytoma.
  • Elaboration of oncogenic activities of E6 an E7 proteins of human papilloma virus (HPV)
Robbins pathologic basis of disease 10th edition has a handful of changes and updates when compared to it's predecessor.  Here is a brief note on the chapterwise updates which are high yield for entrance exams.  **ROBBINS 10TH EDITION CHAPTERWISE UPDATES** **CHAPTER 1- CELL** * ***Satellite DNA****- A major component of centromeres is so-called  satellite DNA, consisting of large arrays—up to megabases  in length—of repeating sequences (from 5 bp up to 5 kb).  Although classically associated with spindle apparatus  attachment, satellite DNA is also important in maintaining  the dense, tightly packed organization of heterochromatin. * * ***Gene Editing and CRISPR- ****An exciting new development that allows high-fidelity  genome editing may usher in the next era of the molecular  revolution. This advance comes from a wholly unexpected  source: the discovery of clustered regularly interspaced short  palindromic repeats (CRISPRs) and CRISPR-associated genes  (Cas), such as the Cas9 nuclease.* **CHAPTER 2- ADAPTATIONS AND INJURY** * ***Ferroptosis- ****Only discovered in 2012, ferroptosis is a distinct  form of cell death that is triggered when excessive intracellular levels of iron or reactive oxygen species overwhelm  the glutathione-dependent antioxidant defenses. * **CHAPTER 3-INFLAMMATION AND REPAIR** * ***Neutrophil extracellular traps (NETs)- ****NETs were mentioned in the previous edition it is further elaborated in the latest edition. Neutrophil extracellular traps (NETs) are extracellular  fibrillar networks that concentrate antimicrobial substances  at sites of infection and trap microbes, helping to prevent  their spread.* **CHAPTER 6- IMMUNITY** * ***Rejection of tissue transplants:*** *Elaborated compared to the previous edition*.  **CHAPTER 7- NEOPLASIA** * ***A few newly added proto-oncogenes: *** 1. FMS-like tyrosine kinase 3 (FLT3) Point mutation or small duplications  in Leukemia.  2. GTP-binding (G) proteins- GNAQ Point mutation in Uveal melanoma.  3. GTP-binding (G) proteins- GNAS Point mutation in Pituitary adenoma.  * ***A few newly added tumor suppessor genes:*** 1. SDHB, SDHD (Succinate dehydrogenase  complex subunits B  and D TCA cycle, oxidative  phosphorylation) seen in Familial paraganglioma, familial  pheochromocytoma.  * ***Elaboration of oncogenic activities of E6 an E7 proteins of human papilloma virus  (HPV)***  1. In the older edition it was mentioned that the E6 protein of HPV inactivates p53. In the 10th edition it is mentioned that in addition to inactivation of p53, E6 protein also increases telomerase expression (TERT).  **CHAPTER 8- INFECTIOUS DISEASES** * *Updates on the SARSCoV2 virus*
Human papilloma virus update Robbins pathology 10th edition
  1. In the older edition it was mentioned that the E6 protein of HPV inactivates p53. In the 10th edition it is mentioned that in addition to inactivation of p53, E6 protein also increases telomerase expression (TERT).

CHAPTER 8- INFECTIOUS DISEASES

  • Updates on the SARSCoV2 virus
Posted in General pathology

Differences between the types of human DNA variations

General Pathology Topics

The two most common forms of human DNA variation in the human genome 1. Single nucleotide polymorphisms (SNPs) and 2. Copy number variations (CNVs).

Let’s looks at a few differences between the two human DNA variations. Very important topic for examinations.

Single nucleotide polymorphisms (SNVs)

  1. SNPs are variants at single nucleotide positions and are almost always biallelic.
  2. Roughly 1% of SNPs occur in coding regions.
  3. SNPs may be useful markers if they happen to be coinherited with a disease-associated polymorphism. In other words, the SNP and the causative genetic factor are in linkage disequilibrium.

Copy number variations

  1. CNVs can be biallelic and simply duplicated or,deleted in some individuals.
  2. Approximately 50% of CNVs involve coding sequences.
  3. CNVs are responsible for 5 million and 24 million base pairs of sequence difference between any two individuals.

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Posted in Hematopathology, WEEKLY QUIZZES

B-Cell Lymphomas and Multiple Myeloma Hematopathology Mcqs

Hematopathology mcqs- Useful for

  • NEET-SS/ DM- Clinical Hematology
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  • American board of hematology.

20 questions- 100 marks

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