Short/Branched Chain Acyl-CoA Dehydrogenase Deficiency
Other Names
SBCAD
2MBCD deficiency
2-methylbutyryl CoA dehydrogenase deficiency
2-methylbutrylglycinuria
Overview
Deficiency of 2-methylbutyryl-CoA dehydrogenase results in the inability to break down isoleucine causing an organic acidemia. This condition is typically found 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. It is now considered a biochemical variant usually with a benign clinical course.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)] More and more cases have been identified by neonatal screening, but they are not published given the benign clinical course.Prenatal Testing
DNA testing or enzyme analysis by amniocentesis or CVS. Prenatal diagnosis is usually not performed given the benign nature of this condition.Clinical Characteristics
With or without treatment, most patients have no clinically significant abnormalities. Symptoms may be triggered by fasting or illness.Initial signs/symptoms may include:
- Nausea
- Vomiting
- Irritability
- Hypoglycemia
- Lethargy
Follow-up Testing after Positive Screen
Quantitative plasma acylcarnitine profile, urine organic acids, urine acylglycine. 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): Newborn Screening Services (see NM providers [3]).
- For evaluation and ongoing collaborative management, consult the following service(s): Pediatric Genetics (see NM providers [3]).
If the Diagnosis is Confirmed
- Educate the family regarding signs, symptoms, and the need for urgent care when the infant becomes ill (see 2-Methylbutyryl CoA Dehydrogenase Deficiency - Information for Parents (STAR-G) for additional information).
- 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.
Genetics in Primary Care Institute (AAP)
Contains health supervision guidelines and other useful resources for the care of children with genetic disorders; 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.
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.
2-Methylbutyryl 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)
Clearinghouse for local, state, and national newborn screening education, programs, policies, and resources. Also, provides
many ways for people to connect and share their viewpoints and questions about newborn screening; supported by the U.S. Department
of Health and Human Services.
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)
Parent centers in every state provide training to parents of children with disabilities and provide information about special
education, transition to adulthood, health care, support groups, local conferences and other federal, state, and local services.
This link has a search tool to help you find the parent center in your state; Department of Education, Office of Special Education.
Tools
ACT Sheet for Elevated C5 Acylcarnitine (ACMG) (
348 KB)
Contains short-term recommendations for clinical follow-up of the newborn who has screened positive; American College of Medical
Genetics.
Confirmatory Algorithms for Elevated C5 Acylcarnitine (ACMG)
An algorithm of the basic steps involved in determining the final diagnosis of an infant with a positive newborn screen; American
College of Medical Genetics.
Services in New Mexico
Newborn Screening Services
See all Newborn Screening Services services providers (3) in our database.
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
Van Calcar SC, Baker MW, Williams P, Jones SA, Xiong B, Thao MC, Lee S, Yang MK, Rice GM, Rhead W, Vockley J, Hoffman G, Durkin
MS.
Prevalence and mutation analysis of short/branched chain acyl-CoA dehydrogenase deficiency (SBCADD) detected on newborn screening
in Wisconsin.
Mol Genet Metab.
2013;110(1-2):111-5.
PubMed abstract / Full Text