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Disease Profile

Alport syndrome

Prevalence
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

Unknown

Age of onset

Adolescent

ICD-10

Q87.8

Inheritance

Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease

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Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype

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X-linked
dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.

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X-linked
recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder

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Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.

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Not applicable

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Other names (AKA)

Alport syndrome, X-linked; Hemorrhagic familial nephritis; Hemorrhagic hereditary nephritis;

Categories

Congenital and Genetic Diseases; Ear, Nose, and Throat Diseases; Eye diseases;

Summary

Alport syndrome is a genetic condition characterized by kidney disease, hearing loss, and eye abnormalities. Most affected individuals experience progressive loss of kidney function, usually resulting in end-stage kidney disease. People with Alport syndrome also frequently develop sensorineural hearing loss in late childhood or early adolescence. The eye abnormalities characteristic of this condition seldom lead to vision loss. In 80% of cases, Alport syndrome is inherited in an X-linked manner and is caused by mutations in the COL4A5 gene. In the remaining cases, it may be inherited in either an autosomal recessive, or rarely in an autosomal dominant manner. In these cases, the condition is caused by mutations in the COL4A3 or COL4A4 genes.[1] Diagnosis of the condition is based on family history of the condition, clinical signs, and specific testing such as a kidney biopsy. The diagnosis can be confirmed by genetic testing. Treatment may include use of a hearing aid, hemodialysis and peritoneal dialysis to treat those with end-stage renal failure, and kidney transplantation.[1][2]

Symptoms

Alport syndrome is characterized by kidney disease, hearing loss, and eye abnormalities. Symptoms typically begin in childhood, and the first sign of the condition is usually the presence of blood in the urine (hematuria). Other symptoms of kidney disease can include having protein in the urine (proteinuria). Over time, an affected person may experience swelling (edema), bone weakening, and joint pain (osteodystrophy). Without treatment, affected individuals will experience end-stage renal disease.[1]

Alport syndrome also causes sensorineural hearing loss, or hearing loss that is due to the inner ear or the nerves not working properly. Hearing loss typically develops during late childhood or early adolescence, and most affected individuals become deaf by age 40. Alport syndrome is also characterized by specific eye changes. Most commonly, affected individuals have an eye finding called anterior lenticonus, which causes the lens to become cone-shaped. Other affected individuals may have abnormal coloration of the retina (dot-and-fleck retinopathy), which can sometimes lead to vision loss. Some individuals may experience maculopathy, or damage to the part of the eye (macula) that allows for central vision.[3][4] 

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Diffuse glomerular basement membrane lamellation
0030034
Thin glomerular basement membrane
0012577
30%-79% of people have these symptoms
Hypertension
0000822
Mesangial hypercellularity
0012574
Proteinuria
High urine protein levels
Protein in urine

[ more ]

0000093
5%-29% of people have these symptoms
Abnormal corneal endothelium morphology
0011488
Anterior lenticonus
0011501
Focal segmental glomerulosclerosis
0000097
Glomerular C3 deposition
0012576
IgA deposition in the glomerulus
0000794
Microscopic hematuria
Small amount of blood in urine
0002907
Nephritis
Kidney inflammation
0000123
Nephrotic syndrome
0000100
Recurrent corneal erosions
Recurrent breakdown of clear protective layer of eye
0000495
Renal glomerular foam cells
0032583
Renal tubular atrophy
0000092
Retinal flecks
0012045
Sensorineural hearing impairment
0000407
Stage 5 chronic kidney disease
0003774
Thickened glomerular basement membrane
0004722
Thickening of glomerular capillary wall
0025005
Tubulointerstitial fibrosis
0005576
1%-4% of people have these symptoms
Aortic aneurysm
Bulge in wall of large artery that carries blood away from heart
0004942
Clitoral hypertrophy
Enlarged clitoris
0008665
Cough
Coughing
0012735
Diffuse leiomyomatosis
0006756
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty

[ more ]

0002015
Dyspnea
Trouble breathing
0002094
Epigastric pain
0410019
Macular degeneration
0000608
Posterior subcapsular cataract
0007787
Recurrent bronchitis
0002837
Stridor
0010307
Vomiting
Throwing up
0002013
Percent of people who have these symptoms is not available through HPO
Corneal erosion
Damage to outer layer of the cornea of the eye
0200020
Developmental cataract
Clouding of the lens of the eye at birth
0000519
Hypoparathyroidism
Decreased parathyroid hormone secretion
0000829
Ichthyosis
0008064
Lenticonus
0001142
Myopia
Close sighted
Near sighted
Near sightedness
Nearsightedness

[ more ]

0000545
Progressive
Worsens with time
0003676
Renal insufficiency
Renal failure
Renal failure in adulthood

[ more ]

0000083
Thrombocytopenia
Low platelet count
0001873
X-linked dominant inheritance
0001423
X-linked inheritance
0001417

Cause

Alport syndrome is caused by mutations in three possible genes: COL4A3, COL4A4, or COL4A5. These genes each provide instructions for making one component of a protein called type IV collagen, which plays an important role in the glomeruli of the kidneys. Glomeruli are clusters of specialized blood vessels that remove water and waste products from the blood and create urine. Mutations in the genes associated with Alport syndrome result in abnormalities of the type IV collagen in glomeruli, which prevent the kidneys from properly filtering the blood. As a result, blood and protein pass into the urine. Over time, the kidneys become scarred, which leads to kidney failure.[1][2]

Type IV collagen is also an important component of the organ of Corti, the inner ear structure that transforms sound waves into nerve impulses for the brain. Alterations in type IV collagen may result in abnormal inner ear functions, which can lead to hearing loss. In addition, type IV collagen plays a role in the eye, where it helps maintain the shape of the lens and the cells of the retina. Mutations found in Alport syndrome may affect the retina and the shape of the lens.[1] 

Diagnosis

Alport syndrome is suspected based on a family history or clinical signs of the condition. A doctor may order a kidney biopsy to look for signs of the condition such as abnormalities of the cells of the glomeruli. A kidney biopsy can also allow to test specifically for type IV collagen protein, as this protein would be absent in a person with Alport syndrome. Doctors may also order a test to measure the amount of blood and protein in the urine. An ophthalmologic exam may be used to look for signs characteristic of the condition such as anterior lenticonus. When Alport syndrome is suspected, genetic testing can be used to confirm the diagnosis and determine the pattern of inheritance. This can provide information about the chance that other family members are affected.[2][5] 

Treatment

Although there is no one specific treatment for Alport syndrome, the goals of treatment include monitoring and controlling progression of the disease and treating the symptoms. Strict control of blood pressure is very important in order to keep the kidneys as healthy as possible. Research suggests that ACE inhibitors, angiotensins, and statins can help reduce proteinuria and the progression of kidney disease. However, treatment of chronic kidney failure often becomes necessary. This can include dietary modifications and fluid restriction. Ultimately, chronic kidney failure progresses to end-stage kidney disease, requiring dialysis or transplantation. Kidney transplantation in people with Alport syndrome is usually successful, but some studies have reported that about 10% of transplanted patients develop inflammation of the kidneys (nephritis).[3][4]

Treatment for other aspects of the condition are addressed as needed. For instance, surgical repairs of the eye manifestations may be recommended. Loss of hearing is likely to be permanent, but affected individuals can be assisted with hearing aids. Counseling and education to increase coping skills can be helpful. Learning new skills such as lip reading or sign language may be of some benefit. Young men with Alport syndrome should use hearing protection in noisy environments. Genetic counseling may be recommended to explain the inherited pattern of the disorder.[2] 

 

Additional information related to the treatment of Alport syndrome can be accessed through GeneReviews and eMedicine

Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Organizations Providing General Support

      Learn more

      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      Where to Start

      • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
      • Genetics Home Reference (GHR) contains information on Alport syndrome. This website is maintained by the National Library of Medicine.
      • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

        In-Depth Information

        • GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
        • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
        • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
        • PubMed is a searchable database of medical literature and lists journal articles that discuss Alport syndrome. Click on the link to view a sample search on this topic.

          References

          1. Alport syndrome. Genetics Home Reference. December 2013; https://ghr.nlm.nih.gov/condition/alport-syndrome.
          2. Meroni M and Sessa A. Alport syndrome. Orphanet. July 2007; https://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=EN&Expert=63.
          3. Silberberg C. Alport syndrome. MedlinePlus. September 22, 2015; https://www.nlm.nih.gov/medlineplus/ency/article/000504.htm.
          4. Saxena R. Alport Syndrome. Medscape Reference. July 21, 2015; https://emedicine.medscape.com/article/238260-treatment#showall.
          5. Kashtan CE. Alport Syndrome and Thin Basement Membrane Nephropathy. GeneReviews. November 25, 2015; https://www.ncbi.nlm.nih.gov/books/NBK1207/.

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