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MANBA

mannosidase beta

The MANBA gene provides instructions for making beta-mannosidase, an enzyme crucial for breaking down specific sugar molecules within cellular lysosomes. The MANBA gene is responsible for producing the beta-mannosidase enzyme, which plays a vital role in the body's metabolic processes.

Chromosome 4q24 Various HGNC:6831 Tier C
MANBA 4q24 p arm q arm 4

MANBA is located on the long (q) arm of chromosome 4, at band 4q24. Arm ratio per GRCh38 - banding schematic.

Explore chromosome 4 in the library →

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Clinical tests that include this

Carrier Screening panel
MANBA is 1 of 1,008 genes on this panel
Expanded carrier screening for recessive and X-linked conditions

Overview

The MANBA gene encodes the beta-mannosidase enzyme, which is involved in the catabolism (breakdown) of oligosaccharides within the lysosomes of cells. Lysosomes are often referred to as the 'recycling centres' of the cell, where waste products are broken down into simpler molecules for reuse or disposal. Dysfunction of this enzyme, due to variants in the MANBA gene, can lead to the accumulation of certain sugar molecules, impacting cellular health.

What the gene does

The beta-mannosidase enzyme, produced from the MANBA gene, is specifically located within the cell's lysosomes. Its primary function is to catalyse the final step in the degradation of certain sugar complexes, known as oligosaccharides, which are typically attached to proteins (glycoproteins). More precisely, beta-mannosidase breaks down disaccharides containing a mannose sugar molecule. This process is essential for the proper recycling of cellular components and preventing the harmful buildup of these complex sugars within the cell.

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Chromosome location

The MANBA gene is situated on the long (q) arm of chromosome 4 at position 24, denoted as 4q24. The human genome contains two copies of chromosome 4, one inherited from each parent. The MANBA gene consists of 16 exons.

Protein structure

Domain architecture has not been experimentally characterised in detail for this protein.

Key variants

Variants within the MANBA gene can affect the production or function of the beta-mannosidase enzyme. These genetic changes can lead to a range of clinical presentations, depending on how severely the enzyme's activity is impaired. The inheritance pattern associated with MANBA-related conditions can vary.

The table below shows the top 10 pathogenic or likely-pathogenic variants currently classified in ClinVar for MANBA.
View all on ClinVar →

Sample of pathogenic variants

10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.

Variant (HGVS) Protein change Classification Evidence Associated condition
c.1398G>A
single nucleotide variant
 p.Trp466Ter Pathogenic ★★☆☆ Beta-D-mannosidosis
c.1434del
Deletion
 p.Lys479fs Pathogenic/Likely pathogenic ★★☆☆ Beta-D-mannosidosis
c.1623G>A
single nucleotide variant
 p.Trp541Ter Pathogenic/Likely pathogenic ★★☆☆ Beta-D-mannosidosis
c.1648C>T
single nucleotide variant
 p.Arg550Ter Pathogenic/Likely pathogenic ★★☆☆ Beta-D-mannosidosis
c.1733del
Deletion
 p.Asn578fs Pathogenic ★★☆☆ Beta-D-mannosidosis
c.1753C>T
single nucleotide variant
 p.Arg585Ter Pathogenic/Likely pathogenic ★★☆☆ Beta-D-mannosidosis
c.2175dup
Duplication
 p.Ser726fs Pathogenic/Likely pathogenic ★★☆☆ Beta-D-mannosidosis
c.544C>T
single nucleotide variant
 p.Arg182Trp Pathogenic/Likely pathogenic ★★☆☆ Beta-D-mannosidosis
c.692G>A
single nucleotide variant
 p.Trp231Ter Pathogenic/Likely pathogenic ★★☆☆ Beta-D-mannosidosis
c.916del
Deletion
 p.Leu306fs Pathogenic/Likely pathogenic ★★☆☆ Beta-D-mannosidosis

Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.

Associated conditions

Variants in the MANBA gene are known to cause beta-mannosidosis, a rare inherited metabolic disorder. This condition arises when the beta-mannosidase enzyme has little or no activity, preventing the proper breakdown of specific sugar molecules. The accumulation of these molecules can lead to various neurological problems and other systemic issues.

No disease links recorded for this gene in our reference set.

UK clinical status

The MANBA gene is included in several UK NHS national genomic testing panels, indicating its recognised clinical significance within the NHS Genomic Medicine Service. It is part of panels for conditions such as Intellectual disability, Likely inborn error of metabolism, and Lysosomal storage disorder, all listed as 'green' in PanelApp, signifying that there is sufficient evidence for its inclusion.

Green-listed
High evidence · clinically actionable in NHS testing
Included in NHS GMS signed-off panels
Likely inborn error of metabolism · R98 NHS GMS → Lysosomal storage disorder · R276 NHS GMS → DDG2P NHS GMS → Intellectual disability NHS GMS →
NHS Genomic Medicine Service Jeen carrier screening

Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory

Frequently asked questions

What is the main role of the MANBA gene?

The MANBA gene provides instructions for making the beta-mannosidase enzyme, which is crucial for breaking down specific sugar molecules within the lysosomes of cells, acting as part of the body's waste recycling system.

What happens if the MANBA gene has a variant?

If the MANBA gene has a variant, the beta-mannosidase enzyme may not function correctly or may be absent, leading to an accumulation of certain sugar molecules in the lysosomes. This can cause beta-mannosidosis, a metabolic disorder with potential neurological effects.

Is MANBA testing available in the UK?

Yes, the MANBA gene is included in several NHS national genomic testing panels in the UK, particularly for conditions related to intellectual disability, inborn errors of metabolism, and lysosomal storage disorders.

References

  1. Molho-Pessach V, Bargal R, Abramowitz Y. Angiokeratoma corporis diffusum in human beta-mannosidosis: Report of a new case and a novel mutation. Journal of the American Academy of Dermatology. 2007. PMID: 17420068
  2. Zhu M, Lovell KL, Patterson JS. Beta-mannosidosis mice: a model for the human lysosomal storage disease. Human molecular genetics. 2006. PMID: 16377659
  3. Gort L, Duque J, Fabeiro JM. Molecular analysis in two beta-mannosidosis patients: description of a new adult case. Molecular genetics and metabolism. 2006. PMID: 16904924
  4. Uchino Y, Fukushige T, Yotsumoto S. Morphological and biochemical studies of human beta-mannosidosis: identification of a novel beta-mannosidase gene mutation. The British journal of dermatology. 2003. PMID: 12890191
  5. Bedilu R, Nummy KA, Cooper A. Variable clinical presentation of lysosomal beta-mannosidosis in patients with null mutations. Molecular genetics and metabolism. 2002. PMID: 12468273
  6. Alkhayat AH, Kraemer SA, Leipprandt JR. Human beta-mannosidase cDNA characterization and first identification of a mutation associated with human beta-mannosidosis. Human molecular genetics. 1998. PMID: 9384606
Educational content. This page is not medical or genetic advice, is not individually reviewed by a clinician for each reader, and should not replace a consultation with a qualified healthcare professional or genetic counsellor. If you are considering genetic testing or acting on a test result, book a consultation.
Data sources Last updated 27 September 2026. Content compiled from HGNC · MedlinePlus Genetics · ClinGen · Genomics England PanelApp · NHS National Genomic Test Directory · ClinVar · UniProt · AlphaFold .