Holt-Oram syndrome

Disease Description (Causes and Symptoms)

• Definition summary: Alport syndrome is an inherited basement membrane disorder mainly caused by genetic variants in the type IV collagen alpha chains (COL4A3, COL4A4, COL4A5), primarily affecting the kidneys (glomerular basement membrane), inner ear (cochlea), and basement membranes of the eyes.
• Pathophysiology: Defects in the COL4 genes cause structural abnormalities of the glomerular basement membrane (splitting, lamellation, and abnormal thickness changes, with a “basket-weave” appearance on electron microscopy), leading to hematuria and proteinuria and eventually progressive deterioration of kidney function. Abnormalities of the basement membrane in the inner ear cause sensorineural hearing loss, while characteristic eye findings include forward protrusion of the anterior lens (anterior cataract/anterior lenticonus).
• Main symptoms:
  • Persistent or recurrent hematuria (often beginning in childhood)
  • Progressive proteinuria and chronic kidney failure (may progress to nephrotic syndrome or end-stage renal disease (ESRD))
  • Sensorineural hearing loss (generally progressive from childhood to adolescence)
  • Eye abnormalities (anterior lenticonus, retinal changes, etc.)
• Inheritance pattern: X-linked inheritance (COL4A5) is most common, but autosomal recessive and dominant forms (COL4A3/COL4A4) also exist. The X-linked form tends to progress more severely in males.

Treatment

• No definitive cure — the main goals are to suppress symptoms and progression and manage complications.
• Medications:
  • ACE inhibitors (or ARBs): Considered most effective for reducing proteinuria and delaying deterioration of kidney function, so early use is recommended. Used to manage blood pressure and reduce proteinuria.
  • Prescriptions to control hypertension and edema when necessary (such as diuretics).
• Procedures/Surgery:
  • Advanced end-stage renal disease (ESRD): Dialysis or kidney transplantation (post-transplant follow-up is necessary).
  • Hearing assistance: Hearing aids and, when necessary, cochlear implants (for severe hearing loss).
  • Eye problems: Ophthalmologic surgery or treatment if vision is reduced due to anterior lenticonus (consult an ophthalmologist).
• Lifestyle management and precautions:
  • Strict blood pressure management (follow the doctor’s recommendations; targets generally follow CKD guidelines).
  • Low-salt diet (for blood pressure and edema management) and restriction of excessive protein intake (adjusted according to kidney status).
  • Avoid nephrotoxic medications (such as nonsteroidal anti-inflammatory drugs).
  • Regular kidney evaluations (blood tests and urinalysis), as well as hearing and vision checks.
  • Vaccination before transplantation and infection prevention (consult the attending doctor if transplantation is planned).
• Complication management:
  • If hypertension, nephrotic syndrome, ESRD, progressive hearing loss, ophthalmologic complications, or other complications occur, treatment should be provided in cooperation with the relevant specialties.

Checklist Before an Outpatient Visit (Including Example Questions)

• Items/materials to prepare or submit:
  • A list of currently used medications (including prescription drugs, over-the-counter medicines, and supplements)
  • Information about family history (hematuria, kidney failure, hearing loss, eye disease, etc.)
  • Recent test results (serum creatinine/estimated GFR, urinalysis, urine protein/creatinine ratio, etc.)
  • Previous kidney biopsy or genetic test results, if available
  • Blood pressure records (home blood pressure log)
  • Notes on the timing and course of changes in hearing and vision
• Items to tell the doctor during the outpatient visit, for example:
  • Whether there has recently been blood in the urine, edema, or weight change
  • When worsening of hearing or vision began and how quickly it has progressed
  • Pregnancy plans (genetic counseling may be necessary)
• Example checklist questions (items for patients to check during the outpatient visit):
  • “Have you recently noticed blood mixed in your urine?”
  • “Have you recently gained weight or developed generalized edema?”
  • “Are any of the medications you usually take nonsteroidal anti-inflammatory drugs?”

Examples of General Questions to Ask the Doctor

• “What is the current status of my kidney function (creatinine/estimated GFR), and what is the likelihood of progression in the future?”
• “What medication should I start, and when, to manage my blood pressure and proteinuria? What side effects should I expect?”
• “How do you determine when kidney transplantation or dialysis is needed? Are there any special precautions after transplantation?”
• “How often should I have regular tests, and how frequently should I visit the necessary specialties (otorhinolaryngology, ophthalmology, etc.)?”

Examples of Disease-Specific Questions

• “Depending on the genetic test results, what is the likelihood of inheritance by family members (children and siblings), and when are genetic counseling and testing recommended?”
• “I (or my child) currently only have hematuria. Should I start an ACE inhibitor (or ARB) immediately, or should we monitor the condition first?”

Note: Diagnosis and treatment vary depending on the individual’s condition. Genetic testing, kidney biopsy, and consultation with specialists may be necessary depending on test results and family history, so consult your attending doctor.