Transthyretin Amyloidosis

Pathophysiology and Types of ATTR

In its normal form, TTR is a tetramer made of four tightly linked subunits. ATTR develops when this tetramer becomes unstable and falls apart into free monomers. The monomers misfold and assemble into insoluble amyloid fibrils that infiltrate tissues.

There are two main types:

• Hereditary ATTR (ATTRv / ATTRm):
  • Cause: An autosomal dominant point mutation in the TTR gene (most commonly V30M, where valine is replaced by methionine at position 30).
  • Features: Onset can be early (age 30–50) or late (> 60). Patients have severe peripheral nerve involvement (polyneuropathy) along with skin and heart damage.
• Wild-type ATTR (ATTRwt):
  • Cause: No gene mutation. With normal aging, the structure of normal (wild-type) TTR gradually becomes unstable.
  • Features: Most common in older men (> 65). It mainly causes hypertrophic cardiomyopathy / heart failure with preserved ejection fraction (HFpEF) and carpal tunnel syndrome in both wrists; severe sensory nerve damage is less common than in ATTRv.

Clinical Features in the Skin, Soft Tissues and Organs

Skin and soft-tissue changes in ATTR are not directly life-threatening, but they are very valuable diagnostic clues:

Skin and Soft-Tissue Signs

• Bruising from fragile vessels (pinch purpura): ATTR fibrils infiltrate and weaken the walls of small blood vessels in the skin. Bruises and patchy bleeding appear spontaneously or after minor trauma, especially on the eyelids, neck, armpits and skin folds.
• Bilateral carpal tunnel syndrome: One of the earliest signs, often appearing 5–10 years before heart involvement. ATTR deposits in the tissues of the carpal tunnel compress the median nerve.
• Shiny yellowish papules around the eyes and face: Smooth, shiny, pale-yellow or waxy papules and plaques can form on the face as amyloid collects in the upper dermis.
• Sweating problems and chronic dry skin: ATTR fibrils around sweat glands and autonomic nerve fibers reduce or stop sweating (anhidrosis), leaving the skin dry and cracked and more prone to infection.

Associated Systemic Features

• Peripheral nerves: Numbness, tingling and burning pain that start in the toes and fingers and gradually move upward, with reduced sensation of temperature and pain.
• Autonomic nerves: Drops in blood pressure on standing, bowel motility problems (chronic diarrhea alternating with constipation) and bladder dysfunction.
• Heart: Infiltrative cardiomyopathy with a thickened heart muscle, arrhythmias and progressive heart failure.

Diagnosis and Screening at Haute-Derma

At Haute-Derma, confirming ATTR follows a structured, step-by-step sequence of clinical and laboratory assessments:

• Clinical assessment and family history: We ask about carpal tunnel syndrome in both wrists, muscle wasting and abnormal sensations in the limbs, and examine for skin bleeding or shiny papules around the eyes. We also ask about heart or nerve disease in the family.
• Biopsy and special stains: A 4 mm punch biopsy of affected skin, or a biopsy of abdominal fat or sweat gland tissue.
  • Congo red staining: deposits stain brick red under ordinary light.
  • Polarized light microscopy: apple-green birefringence confirms the presence of amyloid fibrils.
• Identifying the amyloid protein (typing): Immunohistochemistry (IHC) or mass spectrometry (LC-MS/MS) on the biopsy confirms that the deposit is TTR and clearly distinguishes it from immunoglobulin light chains (AL) or keratin (amyloid K).
• Molecular genetic testing: Sequencing of the TTR gene from a blood sample shows whether an inherited mutation is present. This separates ATTRv (mutation present) from ATTRwt (wild type) and guides genetic counseling for the next generation.
• Assessing the heart and other organs: Technetium-99m PYP cardiac scintigraphy (99mTc-PYP), cardiac MRI (CMR) and NT-proBNP/troponin levels to gauge the extent of heart infiltration.

Modern Treatments and Haute-Derma's Role in Management

Treatment of ATTR has advanced dramatically with targeted biological therapies, moving beyond the symptom-only care of the past:

Targeted Drug Therapies

• TTR stabilizers:
  • Tafamidis: Binds specifically to the thyroxine-binding sites on TTR, holding the tetramer together, preventing breakdown into monomers and limiting amyloid fibril formation. Highly effective for ATTR cardiomyopathy.
• TTR gene silencers:
  • Patisiran / vutrisiran (small interfering RNA, siRNA) or inotersen (antisense oligonucleotide, ASO): These act directly on messenger RNA (mRNA) in the liver, reducing production of both mutant and wild-type TTR and significantly cutting amyloid deposition in nerves and skin.

Supportive Skin Care and Recovery at Haute-Derma

• Protecting blood vessels and reducing skin bleeding: BBL/IPL light treatments at standardized energy levels, combined with topical vessel-supporting products, help calm and reduce bleeding caused by fragile vessels under the skin.
• Supporting skin, vessel and peripheral nerve health: An intensive care plan with antioxidant supplements and tissue-repairing peptides helps improve dry skin, reduce itching and protect the dermal matrix.
• Screening and multidisciplinary coordination: When skin signs or carpal tunnel syndrome raise suspicion of ATTR, Haute-Derma promptly refers patients to trusted cardiology, neurology and genetics centers so targeted treatment can begin without delay.