Short/Branched Chain Acyl-CoA Dehydrogenase Deficiency
Other Names
SBCAD
2-methylbutrylglycinuria
2-methylbutyryl CoA dehydrogenase deficiency
2MBCD deficiency
Overview
Deficiency of 2-methylbutyryl-CoA dehydrogenase results in inability to break down isoleucine causing an organic acidemia. This condition is found mostly by newborn screening and its clinical significance is still unclear. Some of the initially reported patients had neurological symptoms, but their relationship to the metabolic defect remains unclear.Incidence
The condition is rare; less than 20 cases have been reported, primarily among the Hmong population. [Short/Branched Chain Acyl-CoA Dehydrogenase Deficiency - Information for Professionals (STAR-G)]Clinical Characteristics
With treatment, limited experience suggests sequelae may be avoidable. Without treatment, acute neonatal decompensation with neurologic deficits has been described. Most infants and children will not display symptoms in this rare disorder. Symptoms may be triggered by fasting or illness.Initial signs/symptoms may include:
- Nausea
- Vomiting
- Irritability
- Hypoglycemia
- Lethargy
Treatment consists of carnitine supplementation and fasting avoidance. Again, the need for treatment is unclear and continued follow-up and monitoring of these patients seems at present the best course of action.
Follow-up Testing after Positive Screen
Quantitative plasma acylcarnitine profile, urine organic acids, urine acylglycine and acylcarnitine analysis. Urine acylglycine analysis is necessary to exclude this condition.Primary Care Management
Upon Notification of the + Screen
- Contact the family and evaluate the infant for poor feeding, lethargy, vomiting.
- Provide emergency treatment/referral for symptoms of vomiting, lethargy or seizures.
- To confirm the diagnosis, work with the following service(s): see all Newborn Screening Programs services providers (2) in our database.
- For evaluation and ongoing collaborative management, consult the following service(s): we currently have no Pediatric Genetics service providers listed, please search our Services database for related services.
If the Diagnosis is Confirmed
- Educate the family regarding signs, symptoms, and the need for urgent care when the infant becomes ill (see Short/Branched Chain Acyl-CoA Dehydrogenase Deficiency - Information for Parents (STAR-G) for additional information).
- Assist in implementation of a low protein diet and avoidance of fasting.
- Oral L-carnitine may be indicated.
- For those identified after irreversible consequences, assist in management, particularly with developmental and educational interventions.
Specialty Care Collaboration
Initial consultation and ongoing collaboration, particularly for dietary management. Genetic counseling for the family.Resources
Information & Support
For Professionals
Short/Branched Chain Acyl-CoA Dehydrogenase (OMIM)
Extensive review of literature that provides technical information on genetic disorders; Online Mendelian Inheritance in Man
site, hosted by Johns Hopkins University.
National Newborn Screening & Global Resource Center (NNSGRC)
Fact sheets, data reports, publications, and information for clinicians about genetic screening that includes links to state
genetic contacts.
Genetics in Primary Care Institute (AAP)
The goal of this site is to increase collaboration in the care of children with known or suspected genetic disorders. It includes
health supervision guidelines and other useful resources; represents a collaboration among the Health Resources & Services
Administration, the Maternal and Child Health Bureau, and the American Academy of Pediatrics.
For Parents and Patients
Support
Organic Acidemia Association (OAA)
A nonprofit organization that provides information, support, events, connections with other parents, a discussion board,
and nutrition and recipe ideas.
ADHD Resources (Intermountain Healthcare)
ADHD-related tools, forms, and patient education materials; a part of Intermountain Healthcare's Mental Health Integration
Clinical Program.
General
2-methylbutyryl-CoA Dehydrogenase Deficiency (Genetics Home Reference)
Also known as short/branched chain acyl-CoA dehydrogenase deficiency. Excellent, detailed review of condition for patients
and families; U.S. National Library of Medicine.
Short/Branched Chain Acyl-CoA Dehydrogenase Deficiency - Information for Parents (STAR-G)
A fact sheet, written by a genetic counselor and reviewed by metabolic and genetic specialists, for families who have received
an initial diagnosis of this newborn disorder; Screening, Technology and Research in Genetics.
Baby's First Test (Genetic Alliance)
A clearinghouse for newborn screening information. Provides resources about screening at the local, state, and national levels
and ways for people to share their viewpoints and questions about newborn screening; supported by the U.S. Department of Health
and Human Services.
Newborn Screening Information for Families (NNSGRC)
Information for families about genetic screening. Links to support groups, advocacy groups, and state genetic contacts; National
Newborn Screening and Global Resource Center.
Organic Acidemia Association (OAA)
A nonprofit organization that provides information, support, events, connections with other parents, a discussion board,
and nutrition and recipe ideas.
Center for Parent Information and Resources (DOE)
A large resource library related to children with disabilities. Parent Centers in every state provide training to parents
of children with disabilities and provide information about local conferences, support groups, and finding schools and other
local services; Department of Education, Office of Special Education.
Tools
ACT Sheet for Elevated C5 Acylcarnitine (Biotinidase) (ACMG) (
348 KB)
Contains short-term recommendations for clinical follow-up of the newborn who has screened positive; American College of Medical
Genetics.
Isovaleric Acidemia Acute Illness Protocol (NECMP)
A guideline for health care professionals treating the sick infant/child who has previously been diagnosed with isovaleric
acidemia; developed under the direction of Dr. Harvey Levy, Senior Associate in Medicine/Genetics at Children’s Hospital Boston,
and Professor of Pediatrics at Harvard Medical School, for the New England Consortium of Metabolic Programs.
Services
Newborn Screening Programs
See all Newborn Screening Programs services providers (2) in our database.
Pediatric Genetics
We currently have no Pediatric Genetics service providers listed; search our Services database for related services.
For other services related to this condition, browse our Services categories or search our database.
Helpful Articles
Alfardan J, Mohsen AW, Copeland S, Ellison J, Keppen-Davis L, Rohrbach M, Powell BR, Gillis J, Matern D, Kant J, Vockley J.
Characterization of new ACADSB gene sequence mutations and clinical implications in patients with 2-methylbutyrylglycinuria
identified by newborn screening.
Mol Genet Metab.
2010;100(4):333-8.
PubMed abstract / Full Text
These findings confirm that SBCAD deficiency can be identified through newborn screening by acylcarnitine analysis. Our patients
have been well without treatment and call for careful follow-up studies to learn the true clinical impact of this disorder.
Authors
| Reviewing Author: | Nicola Longo, MD, Ph.D. - 7/2011 |
| Compiled and edited by: | Alfred Romeo, RN, Ph.D. - 3/2007 |
| Content Last Updated: | 7/2011 |