Multiplex Ligation-Dependent Probe Amplification (MLPA)

Multiplex ligation-dependent probe amplification (MLPA) is an advanced molecular cytogenetic technique utilized in the laboratory evaluation of genetic and chromosomal disorders.
It operates by detecting chromosomal abnormalities in a highly targeted manner, utilizing specific markers that are intentionally designed for a particular chromosome or a specific chromosomal region.
The technique is specifically tailored to detect submicroscopic chromosomal abnormalities and copy number variants (CNVs) that fall below the resolution of conventional karyotyping.
MLPA is categorized as a rapid diagnostic test, capable of delivering highly precise clinical results within an abbreviated timeframe of just 1 to 2 days.
While it offers speed and precision, a primary limitation of MLPA is its targeted nature; it will exclusively detect abnormalities within the specific, desired chromosomes or regions for which the assay was explicitly designed.
Due to the specialized nature of the markers and the technology involved, MLPA is considered an expensive diagnostic modality.
Unlike next-generation sequencing (NGS), which struggles with detecting large chromosomal rearrangements, large deletions, and methylation defects, MLPA effectively covers these specific diagnostic gaps.

Prenatal Diagnosis: MLPA is highly useful in the prenatal diagnostic setting for the rapid detection of common fetal chromosomal aneuploidies.
Microdeletion/Microduplication Syndromes: It is a primary diagnostic tool for confirming suspected microdeletion and microduplication syndromes when a patient presents with a clinically recognizable phenotype.
Single Gene Disorders: MLPA is frequently deployed to evaluate sequence variations, specifically when a patient's characteristic phenotype suggests a deletion or duplication disorder localized to a single gene.
Carrier Screening: The technique offers precise molecular evaluation for identifying carrier status in specific X-linked or autosomal conditions. For instance, while female carriers of Duchenne muscular dystrophy may exhibit elevated serum creatinine phosphokinase levels, they can be tested much more accurately and conclusively using MLPA.
Imprinting Disorders: A specialized variation of this technique, known as methylation-specific MLPA, is utilized to evaluate and diagnose imprinting disorders that occur secondary to abnormal genomic methylation patterns.

Diagnostic algorithms for neurodevelopmental and genetic disorders dictate specific pathways where MLPA is the preferred testing modality based on the clinical presentation.

Clinical Presentation	Diagnostic Target	Preferred Testing Modalities
Recognizable Syndrome (Common aneuploidies, microdeletion, or microduplication syndromes)	Structural variations (Copy number variants larger than 1 kb)	Karyotype, FISH, QF-PCR, MLPA
Characteristic Phenotype matching a deletion/duplication disorder due to a single gene	Sequence variations (Single nucleotide variants, small insertions/deletions)	Sanger sequencing, MLPA, PCR-based tests
Imprinting Disorders	Abnormal methylation	Methylation-specific MLPA