Dirty Biochemistry Series: Familial Dyslipidemias

Introduction

• Familial Dyslipidemias are difficult to memorize due to complex charts in review textbooks.
• There are six types (one not shown in charts), each with unique deficiencies, lipid buildups, and high-yield findings.
• The lecture aims to simplify memorization using a mnemonic.

Key Mnemonic: "1 LP, 2 LD, B adds V, 3 is E, 4 gets more"

• Purpose: Helps in getting all questions right about familial dyslipidemias.

Breakdown of Familial Dyslipidemias

Type 1: Familial Dyslipidemia

• Mnemonic: "1 LP"
  • LPL (Lipoprotein Lipase) deficiency.
  • Results in triglyceride accumulation.
  • High-yield finding: Pancreatitis.
• Details: Autosomal recessive, buildup includes chylomicrons, triglycerides, cholesterol.

Type 2: Familial Dyslipidemia

• Mnemonic: "2 LD"
  • LDL receptor deficiency.
  • Includes Types 2a and 2b.
  • Associated with tendon xanthomas and corneal arcus.
• Type 2b Addition: "B adds V"
  • Adds VLDL buildup.
  • Differentiation: 2a (LDL buildup), 2b (LDL & VLDL buildup).

Type 3: Familial Dyslipidemia

• Mnemonic: "3 is E"
  • Affects apoE.
  • Results in chylomicrons and VLDL buildup.
  • High-yield finding: Palmar xanthomas.

Type 4: Familial Dyslipidemia

• Mnemonic: "4 gets more"
  • VLDL overproduction.
  • Results in triglyceride buildup.
  • High-yield finding: Pancreatitis.
  • Note: VLDL has more letters than other lipoproteins.

Type 5: Familial Dyslipidemia

• Combination: Type 1 + Type 4 (easy to remember since 1 + 4 = 5).

Additional High-Yield Topic: Abetalipoproteinemia

• Definition: Lack of beta lipoproteins (apoB48, apoB100) in blood.
• Consequences:
  • Issues in fat absorption: Steatorrhea.
  • Decreased fat-soluble vitamins: A and E.
  • Symptoms: Retinitis pigmentosa, spinocerebellar degeneration.
• Histology: Acanthocytes (spiny red blood cells).
• Treatment: High doses of Vitamin E, triglyceride restriction.

Summary

• The mnemonic "1 LP, 2 LD, B adds V, 3 is E, 4 gets more" is crucial for memorization.
• Additional understanding of abetalipoproteinemia helps in broader lipid disorder questions.
• Knowing these key points ensures success in exams like USMLE and COMLEX.