MLPA​ – Multiplex ligation-dependent probe amplification

Overview

Reporting & Results

There are two possible results that can be obtained from an MLPA test:

• Positive (Pathogenic and likely pathogenic): A positive result indicates that a gene deletion or duplication has been identified in association with the disease phenotype under study. This scenario will allow to provide genetic counselling or personal guidance regarding possible medical treatments, disease progression, reproductive-/prevention-strategies and potential implications for other family members
• Negative: A negative result indicates that no disease-causing deletions or duplications were identified in the test performed. It does not guarantee that the induvial will be healthy or free from other genetic disorders or medical conditions. Additionally, a negative result does not rule out a genetic cause of the disease nor does it eliminate the risk for future offspring. However, if a negative test result is obtained and the variant in question is known to be present in affected family members, this then rules out a diagnosis of that genetic disorder in the proband. A negative result may be explained by several causes, including limited genetic knowledge and limitations associated to the used methodology

Sample Requirements

• The following sample types are accepted for Igenomix genetic tests.  
• A thorough labelling of the tube with unique identifying information is suggested, incorrect labelling can lead to rejection of the sample. The minimum required information to identify and accept a sample is – Patient’s full name, Date of birth, Gender and Medical Record Number. 

 For Prenatal Diagnostic:  

• Previous contact with the laboratory is strongly recommended to properly plan the case, prenatal deadlines and anticipate possible inconvenient 
•  Maternal blood sample must be sent with all products of conception, CVS and Amnio samples.  
• Precedence will be given to all prenatal samples.  

The ‘informed consent’ form and the ‘test requisition from’ (included within the provided kit) must be properly filled-in and signed by the patient and sent with the samples inside the shipping box or by e-mail to the laboratory. Igenomix will send you all the documents needed for the pick-up and transportation of the appropriate kit to our laboratory.

Methodology

Limitations

MLPA cannot detect

• Balanced chromosomal rearrangements.
• Telomeric deletions and duplications.
• Deletions and duplications that are outside the target of the MLPA probes used.
• Point mutations, small insertions and deletions.
• Sequence repeats or mutations in the mitochondrial DNA.
• Analytical sensitivity and specificity of the MLPA method are both 99%. 

False positive or negative results may occur due to rare sequence variants in target regions detected by MLPA probes.  A point mutation or polymorphism in the sequence detected by a probe, which results in reduced probe binding efficiency, can also cause a reduction in relative peak area. Therefore, single exon deletions detected by MLPA should always be confirmed by other methods like multiplex PCR or sequencing.