BCKDHB (branched-chain keto acid dehydrogenase E1, beta polypeptide) (eg, maple syrup urine disease) gene analysis, common variants (eg, R183P, G278S, E422X)

CPT4 code

Name of the Procedure:

Branched-Chain Keto Acid Dehydrogenase E1, Beta Polypeptide (BCKDHB) Gene Analysis, Common Variants (e.g., R183P, G278S, E422X)

Summary

This genetic analysis procedure involves examining the BCKDHB gene to identify common variants, such as R183P, G278S, and E422X. This test helps diagnose maple syrup urine disease (MSUD), a rare metabolic disorder.

Purpose

The primary purpose of this genetic test is to diagnose maple syrup urine disease (MSUD), a condition where the body cannot properly process certain amino acids. Identifying BCKDHB gene variants can help determine if a person has MSUD, allowing for early intervention and management.

Indications

Symptoms of MSUD such as sweet-smelling urine, poor feeding, vomiting, lethargy, and developmental delays.
Family history of MSUD.
Newborn screening results indicating possible metabolic disorders.
Consanguinity (closely related parents), which increases the risk of genetic disorders.

Preparation

No fasting or specific preparation required.
Inform the healthcare provider of any medications or supplements being taken.
A blood sample is typically requested, and in some cases, a buccal swab (cheek cell sample) may be used.

Procedure Description

A healthcare professional collects a blood sample or a buccal swab from the patient.
The sample is sent to a specialized genetic lab where DNA is extracted.
The BCKDHB gene is analyzed for specific common variants associated with MSUD.
Results are reviewed by a geneticist, who interprets the findings and reports back to the patient's healthcare provider.

Duration

Sample collection takes approximately 10-15 minutes.
Laboratory analysis usually takes several days to a few weeks.

Setting

Performed in a hospital, outpatient clinic, or specialized genetic laboratory.

Personnel

Healthcare provider or nurse for sample collection.
Medical geneticist and laboratory technicians for sample analysis.

Risks and Complications

Minimal risks involved, primarily associated with blood draw, such as bruising or infection at the puncture site.
Very rare risk of sample contamination leading to inaccurate results.

Benefits

Early, accurate diagnosis of MSUD.
Allows for timely intervention and management of the condition.
Potential to prevent serious complications such as neurological damage and metabolic crises.

Recovery

No recovery time required.
Patients can resume normal activities immediately after sample collection.

Alternatives

Biochemical tests to measure amino acid levels in blood or urine.
Comprehensive newborn screening panels that include metabolic disorder testing.
Each alternative has different degrees of accuracy, specificity, and availability compared to the genetic test.

Patient Experience

Minimal discomfort during sample collection.
No pain or significant discomfort after the sample is taken.
Anxiety related to waiting for genetic test results, which can be managed through support and counseling.