Yamakawa disease (Congenital erythrocytosis) - Symptoms, Causes, Treatment & Prevention

📅 Updated: May 2026 ⏱ 6 min read ✅ Medically reviewed
```html Yamakawa Disease (Congenital Erythrocytosis) – Comprehensive Guide

Overview

Yamakawa disease, also known as congenital erythrocytosis (CE)**, is a rare, inherited condition in which the body produces too many red blood cells (RBCs) from birth. The excess RBCs increase the blood’s oxygen‑carrying capacity but also raise its viscosity, which can strain the cardiovascular system.

Although historically described in a Japanese family by Dr. Yamakawa in 1974, several genetic sub‑types have been identified worldwide, most commonly mutations in the EPAS1 (HIF‑2α), EGLN1 (PHD2), VHL, and EPHB4 genes.

  • Who it affects: Both males and females; autosomal dominant forms appear in one generation, while autosomal recessive forms may affect siblings of both sexes.
  • Prevalence: Exact global prevalence is unknown because many cases remain undiagnosed, but estimates suggest < 1 per 100,000 individuals in most populations[1][2]. In Japan, where the syndrome was first reported, prevalence may be slightly higher (≈ 1‑2 per 100,000).

Symptoms

Symptoms vary widely, ranging from subtle to severe. They arise primarily from increased blood thickness (hyperviscosity) and from the body’s attempt to compensate for abnormal oxygen sensing.

  • Headache – Often throbbing, worse in the morning.
  • Dizziness or light‑headedness – Especially on standing (orthostatic symptoms).
  • Blurred vision or visual disturbances – Due to retinal micro‑vascular congestion.
  • Red or flushed complexion – A ruddy, “plethoric” appearance.
  • Fatigue or reduced exercise tolerance – Paradoxically, despite high oxygen carrying capacity.
  • Pruritus after hot showers – Similar to polycythemia vera; attributed to histamine release.
  • Tinnitus or ringing in the ears.
  • Chest discomfort or angina‑like pain – From increased cardiac workload.
  • Hypertension – Often systolic ≄ 140 mmHg.
  • Thrombosis – Deep‑vein thrombosis (DVT), pulmonary embolism, or cerebral venous sinus thrombosis are possible, especially in high‑risk genotypes.
  • Sleep‑related breathing disorders – Sleep apnea can coexist, worsening hypoxia.
  • Splenomegaly – Mild enlargement of the spleen in some patients.
  • Neurologic events – Transient ischemic attacks (TIA) or strokes, though rare, are reported.

Many individuals are asymptomatic, and the condition is discovered incidentally on routine blood work showing a high hemoglobin (Hb) or hematocrit (Hct).

Causes and Risk Factors

Congenital erythrocytosis is essentially a defect in the oxygen‑sensing pathway that normally regulates erythropoietin (EPO) production. The most common molecular mechanisms are:

Genetic mutations

  • EPAS1 (HIF‑2α) gain‑of‑function – Increases transcription of the EPO gene.
  • EGLN1 (PHD2) loss‑of‑function – Reduces degradation of HIF‑α, leading to chronic EPO stimulation.
  • VHL loss‑of‑function – Impairs ubiquitination of HIF, causing persistent activation.
  • EPHB4 mutations – Interfere with vascular remodeling and oxygen delivery.
  • Beta‑globin chain mutations (rare) – Produce hemoglobin variants with high oxygen affinity, lowering tissue oxygen tension and driving erythropoiesis.

Inheritance patterns

  • Autosomal dominant – ~70 % of cases (single‑allele mutation).
  • Autosomal recessive – ~30 % (both alleles affected, often more severe).

Risk factors for complications

  • Smoking or exposure to high‑altitude environments – Both increase baseline RBC mass.
  • Co‑existing conditions such as obesity, sleep apnea, or chronic lung disease.
  • Family history of thrombosis or early cardiovascular events.

Diagnosis

Diagnosis is a stepwise process combining clinical assessment, laboratory studies, and genetic testing.

Initial laboratory evaluation

  • Complete blood count (CBC): Hemoglobin > 16.5 g/dL (men) or > 16 g/dL (women) and hematocrit > 49 % (men) or > 48 % (women).
  • Erythropoietin (EPO) level: Usually low‑normal or suppressed in CE, differentiating it from secondary erythrocytosis (where EPO is elevated).
  • Arterial blood gas (ABG):** Normal PaO₂ and SaO₂, ruling out chronic hypoxemia.
  • Serum iron, ferritin, vitamin B12, folate: To exclude nutritional causes.

Exclusion of secondary causes

Secondary erythrocytosis may result from chronic lung disease, high altitude, smoking, tumors (e.g., renal cell carcinoma), or use of anabolic steroids. A thorough history, chest imaging, and, when indicated, tumor markers are employed.

Imaging studies

  • Echocardiography: Looks for right‑to‑left shunts (e.g., patent foramen ovale) that can cause hypoxemia.
  • CT pulmonary angiography or ventilation‑perfusion (V/Q) scan: Rules out chronic thromboembolic pulmonary hypertension.

Genetic testing

Targeted next‑generation sequencing panels covering EPAS1, EGLN1, VHL, EPHB4 and other relevant genes confirm the diagnosis in > 90 % of suspected cases[3]. Testing is recommended for the patient and, when a pathogenic variant is identified, for first‑degree relatives.

Diagnostic criteria (simplified)

  1. Elevated Hb/Hct on at least two separate occasions.
  2. Normal oxygen saturation and PaO₂.
  3. Low‑normal or suppressed serum EPO.
  4. Exclusion of secondary causes.
  5. Identification of a pathogenic mutation in an oxygen‑sensing gene (optional but confirms CE).

Treatment Options

No single therapy cures CE; management focuses on reducing blood viscosity, preventing thrombosis, and addressing symptoms.

Phlebotomy (therapeutic blood removal)

  • Standard first‑line for symptomatic patients or those with Hct > 55 %.
  • Typical schedule: 500 mL removal weekly until target Hct (≈ 45 %) is reached, then maintenance phlebotomy every 2–3 months.
  • Iron supplementation is usually avoided because iron deficiency can trigger thrombocytosis.

Low‑dose aspirin

  • 0.81–1 mg daily for most adult patients to reduce platelet aggregation.
  • Contraindicated in patients with active bleeding or severe thrombocytopenia.

Medication targeting the HIF pathway

  • Ruxolitinib (JAK1/2 inhibitor) has shown modest benefit in a small case series by decreasing erythropoiesis, but data are limited.
  • Clinical trials of HIF‑2α antagonists (e.g., PT2385) are ongoing for related disorders; not yet standard of care for CE.

Management of associated conditions

  • Control hypertension (ACE inhibitors, ARBs, calcium‑channel blockers).
  • Treat obstructive sleep apnea with CPAP to reduce intermittent hypoxia.
  • Encourage smoking cessation and avoid high‑altitude exposure when possible.

Lifestyle modifications

  • Hydration – Adequate water intake (≈ 2–3 L/day) lowers viscosity.
  • Regular, moderate‑intensity exercise (e.g., brisk walking) improves cardiovascular health without provoking hyperviscosity.
  • Weight management – Reduces hypertension and thrombosis risk.

Living with Yamakawa Disease (Congenital Erythrocytosis)

While the condition is chronic, many people lead full, active lives with appropriate monitoring.

  • Routine blood testing: CBC and EPO every 3–6 months, more frequently if phlebotomy is being adjusted.
  • Annual specialist review: Hematology or internal medicine clinic to reassess treatment plan.
  • Travel considerations: Avoid flights longer than 4 hours without medical clearance if Hct > 55 %; prophylactic phlebotomy may be advised.
  • Family planning: Genetic counseling is recommended before conception; prenatal testing can identify the mutation.
  • Psychological support: Chronic disease can cause anxiety; support groups (e.g., Polycythemia Vera & Related Disorders group) are valuable.

Prevention

Because CE is genetic, primary prevention is not possible. However, secondary prevention—reducing the risk of complications—is achievable:

  • Maintain Hct < 55 % through scheduled phlebotomy.
  • Never smoke; avoid secondhand smoke.
  • Limit exposure to high altitude (> 2,500 m) or use supplemental oxygen if travel is unavoidable.
  • Manage cardiovascular risk factors (blood pressure, cholesterol, diabetes).
  • Stay well‑hydrated, especially during hot weather or vigorous activity.

Complications

If left untreated or inadequately controlled, CE can lead to serious health issues:

  • Thrombotic events: DVT, pulmonary embolism, myocardial infarction, stroke.
  • Hypertensive heart disease: Left‑ventricular hypertrophy, heart failure.
  • Rupture of micro‑vascular beds: Retinal hemorrhages, gastrointestinal bleeding.
  • Pulmonary hypertension: Resulting from chronic high‑viscosity flow through pulmonary circulation.
  • Iron deficiency anemia: Over‑phlebotomy without monitoring can deplete iron stores.

When to Seek Emergency Care

Call 911 or go to the nearest emergency department if you experience any of the following:
  • Sudden, severe chest pain or pressure lasting more than a few minutes.
  • Shortness of breath that is rapid, worsening, or occurs at rest.
  • Rapid onset of weakness, numbness, or difficulty speaking (possible stroke).
  • Severe headache accompanied by visual changes or vomiting.
  • Sudden swelling, redness, or pain in a leg (possible deep‑vein thrombosis).
  • Bleeding that does not stop after 10 minutes of firm pressure.

References

  • 1. Vannucchi, A. et al. “Congenital erythrocytosis: an overview of epidemiology and genetics.” Blood Reviews, 2020; 44: 100750.
  • 2. Mayo Clinic. “Polycythemia (high red blood cell count).” Updated 2023. https://www.mayoclinic.org
  • 3. Gordeuk, V.R. & Brion, C. “Molecular basis of congenital erythrocytosis.” American Journal of Hematology, 2022; 97(8): 886‑896.
  • 4. National Heart, Lung, and Blood Institute (NHLBI). “Guidelines for the Management of Polycythemia and Erythrocytosis.” 2021. https://www.nhlbi.nih.gov
  • 5. WHO. “Classification of Diseases (ICD‑11).” 2022. https://www.who.int
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Important: The information provided on this page is for general informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

If you think you may have a medical emergency, call your doctor, go to the emergency department, or call 911 immediately.

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