Inherited metabolic disorders refer to different types of medical conditions caused by genetic defects — most commonly inherited from both parents — that interfere with the body's metabolism. Metabolism is the complex set of chemical reactions that your body uses to maintain life, including energy production. Special enzymes break down food or certain chemicals so your body can use them right away for fuel or store them. Also, certain chemical processes break down substances that your body no longer needs, or make those it lacks.

When these chemical processes don't work properly due to a hormone or enzyme deficiency, a metabolic disorder occurs. Inherited metabolic disorders fall into different categories, depending on the specific substance and whether it builds up in harmful amounts (because it can't be broken down), it's too low, or it's missing. Some metabolic disorders can be diagnosed by routine screening tests done at birth. Others are identified only after a child or adult shows symptoms of a disorder.

  • Experience. Mayo Clinic is among the top medical centers in testing, diagnosis and treatment of inherited metabolic disorders. Experience is important because there are so many types of inherited metabolic disorders and their symptoms can mimic more common diseases or conditions, making them difficult to diagnose.
  • Expertise and team approach. The key to accurate diagnoses of inherited metabolic disorders includes coordination among different medical specialties. Depending on the type and severity of the disorder and your age, your Mayo Clinic team of experts may include specialists in pediatrics, developmental pediatrics, neurology, endocrinology, medical genetics, nutrition and other areas.
  • Newest tests. Mayo Medical Laboratories offers comprehensive testing for inherited metabolic disorders. The Biochemical Genetics Laboratory at Mayo Clinic, one of the largest laboratories of its kind nationwide, uses other state-of-the-art methods to identify inherited metabolic disorders and offers supplemental newborn screening. Identifying inherited metabolic disorders in newborns before symptoms appear can dramatically improve outcomes. The Molecular Generics Laboratory offers DNA and molecular testing.

Types

Inherited metabolic disorders fall into different categories, depending on whether a specific substance (such as amino acids, fats, proteins or carbohydrates) builds up in harmful amounts or is too low or missing. There are thousands of inherited metabolic disorders, caused by different genetic defects. Examples include:

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    Specialists at Mayo Clinic in Florida treat adults with inherited metabolic disorders. Medical specialists involved in testing, diagnosis and treatment vary, depending on the type of disorder and symptoms. The team may include specialists in neurology, endocrinology, genetics, nutrition and several other areas.

    For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

    Specialists at Mayo Clinic in Florida treat adults with inherited metabolic disorders. Medical specialists involved in testing, diagnosis and treatment vary, depending on the type of disorder and symptoms. The team may include specialists in neurology, endocrinology, genetics, nutrition and several other areas.

    For appointments or more information, call the Central Appointment Office at 904-953-0853 8 a.m. to 5 p.m. Eastern time, Monday through Friday or complete an online appointment request form.

    Specialists at Mayo Clinic in Minnesota treat children and adults with inherited metabolic disorders. Medical specialists involved in testing, diagnosis and treatment vary, depending on the type of disorder and symptoms. The team may include specialists in neurology, pediatrics, endocrinology, medical genetics, nutrition and several other areas.

    For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

    At Mayo Clinic in Minnesota, children are seen by doctors in many specialty areas, ensuring that they receive the best care for their type of disorder, as well as their age and size. Metabolic disorders may be treated by specialists in pediatric neurology, developmental pediatrics, endocrinology, medical genetics, nutrition and several other areas. Pediatric specialists at Mayo Clinic support the family and understand the unique aspects of caring for children.

    For appointments or more information, call the Central Appointment Office at 507-538-3270 7 a.m. to 6 p.m. Central time, Monday through Friday or complete an online appointment request form.

    See information on patient services at the three Mayo Clinic locations, including transportation options and lodging.

    People with inherited metabolic disorders may have a variety of symptoms without a diagnosis, or they may have been misdiagnosed. Parents often come to Mayo Clinic because their child has several symptoms such as developmental delays, birth defects, an abnormally small head or brain, seizures, abnormal movements, growth problems, or others. In some cases, children may have been misdiagnosed with cerebral palsy, autism or other conditions whose symptoms can be similar to inherited metabolic disorders.

    Tests and assessments may include a biopsy of the skin or other tissue, magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), spinal tap (lumbar puncture), and an electromyography (EMG), which includes a nerve conduction study. In tests that involve radiation, specialists carefully monitor doses to avoid the risk of radiation overexposure.

    Other tests and evaluations may include:

    • Genetic evaluation. The Department of Medical Genetics at Mayo Clinic in Minnesota provides evaluations for children and adults. Specialists perform a thorough physical exam and discuss family history. They may also order genetic testing and provide genetic counseling.
    • Genetic testing. Mayo offers comprehensive biochemical and molecular testing for inherited metabolic disorders, from supplemental newborn screening to follow-up testing and diagnosis.
    • Genetic counseling. People diagnosed with an inherited metabolic disorder and their families will receive counseling from medical specialists in genetics to explain the diagnosis and the role of inherited genes. If one person in the family has an inherited metabolic disorder, specialists often recommend genetic counseling and testing for other family members as well.
    • Neurological assessment. For children with neurological problems, specialists in Mayo's Child and Adolescent Neurology Subspecialty Group in Minnesota will perform various tests, including an extensive physical exam and certain screenings, such as vision, hearing, heart and liver. The exam will include a detailed medical history of the child and the extended family. Older children, teens and adults may also receive neuropsychological testing. Adult neurologists will provide initial assessments for adults and may recommend a neurometabolic consultation.

    Treatment for an inherited metabolic disorder depends on the type and severity, how much the disorder affects body or brain functions, options for participating in a clinical trial and other considerations. Because there are so many types of inherited metabolic disorders, treatment recommendations may vary considerably — from dietary restrictions, certain vitamins or other therapies to medication or surgery.

    Mayo Clinic also offers:

    • Other assessments and treatments. Certain inherited metabolic disorders may also increase risk of other conditions, such as heart, vision or hearing problems. For those at risk of developing such problems, the doctor may recommend regular heart, vision or hearing checkups and treatments.
    • Supportive care. For some inherited metabolic disorders, such as Tay-Sachs disease, currently there is no cure. In these cases, Mayo Clinic provides supportive care for children and their families in coordination with their local health providers.

    Mayo Clinic is on the forefront of research for inherited metabolic disorders, ranging from studies on genetic defects to development of new treatment options.

    Publications

    See a list of publications by Mayo Clinic doctors on inherited metabolic disorders on PubMed, a service of the National Library of Medicine.

    Nov. 19, 2012