Última actualización:
June 01, 2022
Años publicados: 1987, 1988, 1990, 1997, 2001, 2010, 2013, 2016
NORD gratefully acknowledges Joseph R. Bloomer, MD, Professor of Medicine and Genetics, Director of the Liver Center, Director of the Porphyria Center, University of Alabama at Birmingham, for assistance in the preparation of this report.
Summary
ALAD porphyria is a very rare genetic metabolic disease characterized by almost complete deficiency of the enzyme delta-aminolevulinic acid (ALA) dehydratase. Deficiency of this enzyme leads to the accumulation of the porphyrin precursor ALA, which can potentially result in a variety of symptoms. Symptoms vary from one person to another, but usually come from the neurological and gastrointestinal systems. This disease is inherited as an autosomal recessive disorder.
Introduction
ALAD porphyria is in the group of disorders known as the porphyrias. The porphyrias are characterized by abnormally high levels of porphyrins and porphyrin precursors in the body due to deficiencies of enzymes essential to the creation (synthesis) of heme, a part of hemoglobin. There are at least seven types of porphyria. The symptoms associated with the various types of porphyria differ. It is important to note that people who have one type of porphyria do not develop any of the other types. Porphyrias are generally classified into two groups: the «hepatic» and «erythropoietic» types. Porphyrins and related substances originate in excess amounts from the liver in the hepatic types, and mostly from the bone marrow in the erythropoietic types. ALAD porphyria is a hepatic form of porphyria.
The onset, severity and type of symptoms can vary greatly in individuals with a specific type of porphyria. This variation may depend on, in part, the amount of residual enzyme activity in each individual. Individuals with more significant enzyme deficiency may have more severe symptoms and earlier onset. Individuals with partial deficiency will have milder symptoms, and some individuals will not develop any symptoms (asymptomatic). It is important to note that affected individuals may not have all of the symptoms discussed below. Affected individuals should talk to their medical team about their specific case, associated symptoms and overall prognosis.
Individuals with ALAD porphyria may have bouts or “attacks” when symptoms are intense, which are referred to as neurovisceral or acute attacks. An attack may last for several weeks. During an attack, affected individuals may experience severe abdominal cramping or pain accompanied by vomiting and constipation. During infancy, gastrointestinal abnormalities may cause an affected child to fail to grow and gain weight as expected.
Several other neurological symptoms can occur during an acute attack due to problems with the nerves outside the central nervous system (peripheral neuropathy), resulting in numbness or tingling in the hands and feet, burning pain, sensitivity to touch, and a lack of coordination. In severe cases, the motor nerves are involved, resulting in loss or partial impairment of the ability to use voluntary muscles. ALAD porphyria can also be associated with psychological changes during an acute attack. In severe cases, loss of contact from reality (psychosis) has been reported.
Additional symptoms that occur during acute attacks include a rapid heartbeat (tachycardia), high blood pressure (hypertension), seizures, and breathing (respiratory) impairment.
ALAD porphyria is caused by mutations in the ALAD gene, and the disease is inherited as an autosomal recessive disorder. This means that both copies of the ALAD gene have a mutation. Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.
Recessive genetic disorders occur when an individual inherits two copies of an abnormal gene for the same trait, one from each parent. If an individual inherits one normal gene and one gene for the disease, the person will be a carrier for the disease but usually will not show symptoms. The risk for two carrier parents to both pass the altered gene and have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents is 25%. The risk is the same for males and females. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.
The ALAD gene contains instructions for creating the enzyme aminolevulinate dehydratase (ALAD), which is necessary for the production of heme. Heme is part of hemoglobin, which is the oxygen-carrying component of red blood cells. Heme is mainly produced in the bone marrow and the liver. Eight different enzymes are necessary for the creation of heme.
Mutations of the ALAD gene result in deficient levels ofporphobilinogen in the body, with accumulation of ALA, which causes the symptoms associated with ALAD porphyria.
A variety of different triggers have been identified that can precipitatean acute attack in individuals with ALAD porphyria. These triggers include alcohol, certain drugs, physical and psychological stress, infection, fasting (reduced caloric intake) and dehydration. The use of estrogen or progesterone is also suspect of triggering an acute attack.
ALAD porphyria is an extremely rare disorder with few cases reported in the medical literature. Most cases have occurred in Europe. However, the disorder can potentially occur in any population. More males have been identified with ALAD porphyria than females in the medical literature, but the disorder affects probably males and females in equal numbers. Researchers suspect that some cases of ALAD porphyria go undiagnosed or misdiagnosed, making it difficult to estimate the true frequency of this disorder in the general population. The onset of ALAD porphyria is usually during infancy or childhood, but late-onset of the disorder (well into adult life) has also been reported.
A diagnosis of ALAD porphyria is made based upon identification of characteristic symptoms, a detailed patient history, and a thorough clinical evaluation and of specialized tests that can detect delta-aminolevulinic acid in the urine.
Molecular genetic testing can confirm a diagnosis of ALAD porphyria by identifying the characteristic genetic mutation that causes the disorder.
Treatment
The treatment of ALAD porphyria is directed toward the specific symptoms that are present in each individual. Because there have been so few cases of ALAD porphyria, there is only limited information on treatment for the disorder.
Avoidance of triggering factors such as alcohol, certain drugs, fasting, and low carbohydrate diets is recommended for affected individuals. The specific drugs that may need to be avoided in one person can differ from the drugs that need to be avoided in another. More information on these preventive measures and a list of drugs that may potentially need to be avoided are available from the American Porphyria Foundation (see Resources section of this report).
Two standard treatments for acute porphyrias in general are intravenous infusions of hemin and supplementation with glucose. However, these therapies have not been universally effective in treating individuals with ALAD porphyria.
Hemin is an orphan drug that has been approved by the Food and Drug Administration (FDA) for the treatment of acute porphyria. The drug known as Panhematin® (hemin for injection) is usually given to treat an acute attack. The drug is manufactured by:
Recordati Rare Diseases, Inc.
100 Corporate Drive
Lebanon, NJ 08833
Tel. 908-236-0888
If hemin cannot be obtained quickly enough, glucose administration both orally and intravenously (which has similar effect to hemin) may be used to treat individuals with ALAD porphyria.
Additional drugs may be used to treat affected individuals during an acute attack including pain medications such as opiates, beta-adrenergic blocking agents such as propranolol to treat a rapid heartbeat, sedatives to calm nerves, drugs that reduce nausea and vomiting (anti-emetics) and anti-seizure medications (anti-convulsants). In addition, intravenous fluid replacement may be necessary during an acute attack to ensure that proper fluid and electrolyte levels are maintained.
Individuals with ALAD porphyria should carry Medic Alert bracelets or wallet cards. Genetic counseling may be of benefit for affected individuals and their families.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
For information about clinical trials sponsored by private sources, contact:
www.centerwatch.com
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
TEXTBOOKS
Strachan T and Read A. Human Molecular Genetics. 4th Edition. Garland Science, Taylor and Francis Group, LLC; New York, NY; 2011.
Lichtman MA, Beutler E, Kipps TJ, Selisohn U, et al. Eds. Williams Hematology. 7th ed. McGraw-Hill Companies. New York, NY; 2006:813-816.
JOURNAL ARTICLES
Jaffe EK, Stith L. ALAD porphyria is a conformational disease. Am J Hum Genet. 2007;80:329-337.
Hedger RW, Wehrmacher WH, French AV. Porphyria syndrome associated with diabetic nephrosclerosis and erythropoietin. Compr Ther 2006; 32(3) 163-171.
Sassa S. Modern diagnosis and management of the porphyrias. Br J Haematol. 2006;134:281-292.
Akagi R, Kato N, Inoue R, Anderson KE, Sassa S. delta-aminolevulinate dehydratase (ALAD) porphyria: the first case in North America with two novel ALAD mutations. Mol Genet Metab. 2006;87:329-326.
Anderson KE, Bloomer JR, Bonkovsky HL, et al. Recommendations for the diagnosis and treatment of the acute porphyrias. Ann Int Med 2005; 142:439-450.
Doss MO, Stauch T, Gross U, et al. The third case of Doss porphyria (delta-amino-levulinic acid dehydratase deficiency) in Germany. J Inherit Metab Dis. 2004;27:529-536.
INTERNET
Sinha S, Gascon P, Schwartz RA, Shumate MJ. ALA Dehydratase Deficiency Porphyria. Medscape Reference, Last Update March 26, 2015. Available at: https://emedicine.medscape.com/article/198248-overview Accessed April 12, 2016.
National Digestive Diseases Clearinghouse. Porphyria. Last Update February 2014. Available at: https://digestive.niddk.nih.gov/ddiseases/pubs/porphyria/ Accessed April 12, 2016.
Deybach JC. Porphyria due to ALA dehydratase deficiency. Orphanet. Last Update February 2009. Available at: https://www.orpha.net/consor/cgi-bin/Disease_Search.php?lng=EN&data_id=14678&Disease_Disease_Search_diseaseGroup=Porphyria-due-to-ALA-dehydratase-deficiency&Disease_Disease_Search_diseaseType=Pat&Disease(s)/group%20of%20diseases=Porphyria-due-to-ALA-dehydratase-deficiency&title=Porphyria-due-to-ALA-dehydratase-deficiency&search=Disease_Search_Simple Accessed April 12, 2016.
McKusick VA., ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No: 612740; Last Update: 02/27/2012. Available at: https://omim.org/entry/612740 Accessed April 12, 2016.
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Aprende más https://rarediseases.org/patient-assistance-programs/caregiver-respite/The information provided on this page is for informational purposes only. The National Organization for Rare Disorders (NORD) does not endorse the information presented. The content has been gathered in partnership with the MONDO Disease Ontology. Please consult with a healthcare professional for medical advice and treatment.
The Genetic and Rare Diseases Information Center (GARD) has information and resources for patients, caregivers, and families that may be helpful before and after diagnosis of this condition. GARD is a program of the National Center for Advancing Translational Sciences (NCATS), part of the National Institutes of Health (NIH).
View reportOrphanet has a summary about this condition that may include information on the diagnosis, care, and treatment as well as other resources. Some of the information and resources are available in languages other than English. The summary may include medical terms, so we encourage you to share and discuss this information with your doctor. Orphanet is the French National Institute for Health and Medical Research and the Health Programme of the European Union.
View reportOnline Mendelian Inheritance In Man (OMIM) has a summary of published research about this condition and includes references from the medical literature. The summary contains medical and scientific terms, so we encourage you to share and discuss this information with your doctor. OMIM is authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine.
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