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Mucopolysaccharidosis, MPS-III-B(MPS3B)

MedGen UID:
88601
Concept ID:
C0086648
Disease or Syndrome
Synonyms: MPS 3B; MPS III B; MPS3B; Mucopoly-saccharidosis type 3B; Mucopolysaccharidosis type IIIB (Sanfilippo B); MUCOPOLYSACCHARIDOSIS, TYPE IIIB; N-acetyl-alpha-d-glucosaminidase deficiency; NAGLU DEFICIENCY; Sanfilippo syndrome B
SNOMED CT: MPS III-B - Mucopolysaccharidosis III-B (59990008); Sanfilippo syndrome B (59990008); Alpha-N-acetylglucosaminidase deficiency (59990008); MPSIIIB - Mucopolysaccharidosis type IIIB (59990008); N-Acetyl-alpha-D-glucosaminidase deficiency (59990008); Mucopolysaccharidosis III-B (59990008); Mucopolysaccharidosis, MPS-III-B (59990008); Sanfilippo syndrome, type B (59990008); alpha-N-acetylglucosaminidase deficiency (59990008)
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
141025
Concept ID:
C0441748
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
 
Gene (location): NAGLU (17q21.2)
 
Monarch Initiative: MONDO:0009656
OMIM®: 252920
Orphanet: ORPHA79270

Disease characteristics

Excerpted from the GeneReview: Mucopolysaccharidosis Type III
Mucopolysaccharidosis type III (MPS III) is a multisystem lysosomal storage disease characterized by progressive central nervous system degeneration manifest as severe intellectual disability (ID), developmental regression, and other neurologic manifestations including autism spectrum disorder (ASD), behavioral problems, and sleep disturbances. Disease onset is typically before age ten years. Disease course may be rapidly or slowly progressive; some individuals with an extremely attenuated disease course present in mid-to-late adulthood with early-onset dementia with or without a history of ID. Systemic manifestations can include musculoskeletal problems (joint stiffness, contractures, scoliosis, and hip dysplasia), hearing loss, respiratory tract and sinopulmonary infections, and cardiac disease (valvular thickening, defects in the cardiac conduction system). Neurologic decline is seen in all affected individuals; however, clinical severity varies within and among the four MPS III subtypes (defined by the enzyme involved) and even among members of the same family. Death usually occurs in the second or third decade of life secondary to neurologic regression or respiratory tract infections. [from GeneReviews]
Authors:
Victoria F Wagner  |  Hope Northrup   view full author information

Additional descriptions

From OMIM
Sanfilippo syndrome B is an autosomal recessive lysosomal storage disorder characterized by the accumulation of heparan sulfate. Clinically, patients have progressive neurodegeneration, behavioral problems, mild skeletal changes, and shortened life span. The clinical severity ranges from mild to severe (Chinen et al., 2005). For a phenotypic description and a discussion of genetic heterogeneity of Sanfilippo syndrome, or mucopolysaccharidosis III, see MPS IIIA (252900).  http://www.omim.org/entry/252920
From MedlinePlus Genetics
People with MPS III often have a slightly enlarged liver (mild hepatomegaly) or spleen (mild splenomegaly), and a soft out-pouching around the belly-button (umbilical hernia) or lower abdomen (inguinal hernia). Cardiac abnormalities may also occur in this condition, including weakening of the heart muscle (cardiomyopathy), disruption of the heart's normal rhythm (arrhythmia), or problems with the heart's valves. Affected individuals often experience chronic diarrhea and recurrent upper respiratory and ear infections. People with MPS III may also have hearing loss and vision problems.

The physical features of MPS III are less pronounced than those of other types of mucopolysaccharidosis. Individuals with MPS III typically have mildly "coarse" facial features, a prominent forehead, a large head (macrocephaly), and thick hair and eyebrows. Some people with MPS III have short stature, joint stiffness, or mild dysostosis multiplex, which refers to multiple skeletal abnormalities seen on x-ray. 

MPS III is divided into types IIIA, IIIB, IIIC, and IIID, which are distinguished by their genetic cause. The different types of MPS III have similar signs and symptoms, although the features of MPS IIIA typically appear earlier in life and progress more rapidly. People with MPS III usually live into adolescence or early to mid-adulthood.

People with MPS III generally do not display any features of the condition at birth, but they begin to show signs and symptoms of the disorder during early childhood. Early signs and symptoms of MPS III can include frequent ear and throat infections or bowel problems, though most common are mild developmental delay or delayed speech. Behavioral problems often worsen with affected children becoming restless, hyperactive, destructive, anxious, impulsive, fearless, or aggressive. Some affected children display features of autism spectrum disorder, which is a condition characterized by difficulty with social interactions and communication. Children with MPS III may have an increased tendency to chew on objects or put things in their mouth (be hyperoral). Sleep disturbances are also very common in children with MPS III. This condition causes progressive intellectual disability and the loss of previously acquired skills (developmental regression or dementia). In later stages of the disorder, people with MPS III may develop seizures, loss of mobility, and movement disorders.

Mucopolysaccharidosis type III (MPS III), also known as Sanfilippo syndrome, is a disorder that primarily affects the brain and spinal cord (central nervous system). It is characterized by deterioration of neurological function (neurodegeneration), resulting in many of the features of the condition. Other body systems can also be involved, although the physical features are usually mild in the early stages.  https://medlineplus.gov/genetics/condition/mucopolysaccharidosis-type-iii

Clinical features

From HPO
Heparan sulfate excretion in urine
MedGen UID:
340721
Concept ID:
C1854827
Finding
An increased concentration of heparan sulfates in the urine.
Cardiomegaly
MedGen UID:
5459
Concept ID:
C0018800
Finding
Increased size of the heart, clinically defined as an increased transverse diameter of the cardiac silhouette that is greater than or equal to 50% of the transverse diameter of the chest (increased cardiothoracic ratio) on a posterior-anterior projection of a chest radiograph or a computed tomography.
Asymmetric septal hypertrophy
MedGen UID:
104705
Concept ID:
C0205700
Disease or Syndrome
Hypertrophic cardiomyopathy with an asymmetrical pattern of hypertrophy, with a predilection for the interventricular septum and myocyte disarray.
Diarrhea
MedGen UID:
8360
Concept ID:
C0011991
Sign or Symptom
Abnormally increased frequency (usually defined as three or more) loose or watery bowel movements a day.
Hepatomegaly
MedGen UID:
42428
Concept ID:
C0019209
Finding
Abnormally increased size of the liver.
Hearing impairment
MedGen UID:
235586
Concept ID:
C1384666
Disease or Syndrome
A decreased magnitude of the sensory perception of sound.
Aggressive behavior
MedGen UID:
1375
Concept ID:
C0001807
Individual Behavior
Behavior or an act aimed at harming a person, animal, or physical property (e.g., acts of physical violence; shouting, swearing, and using harsh language; slashing someone's tires).
Seizure
MedGen UID:
20693
Concept ID:
C0036572
Sign or Symptom
A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.
Sleep abnormality
MedGen UID:
52372
Concept ID:
C0037317
Finding
An abnormal pattern in the quality, quantity, or characteristics of sleep.
Hyperactivity
MedGen UID:
98406
Concept ID:
C0424295
Finding
Hyperactivity is a condition characterized by constant and unusually high levels of activity, even in situations where it is deemed inappropriate.
Progressive neurologic deterioration
MedGen UID:
381506
Concept ID:
C1854838
Finding
Intellectual disability
MedGen UID:
811461
Concept ID:
C3714756
Mental or Behavioral Dysfunction
Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.
Joint stiffness
MedGen UID:
56403
Concept ID:
C0162298
Sign or Symptom
Joint stiffness is a perceived sensation of tightness in a joint or joints when attempting to move them after a period of inactivity. Joint stiffness typically subsides over time.
Thickened ribs
MedGen UID:
98096
Concept ID:
C0426820
Finding
Increased thickness (diameter) of ribs.
Dense calvaria
MedGen UID:
343213
Concept ID:
C1854834
Finding
An abnormal increase of density of the bones making up the calvaria.
Ovoid thoracolumbar vertebrae
MedGen UID:
401469
Concept ID:
C1868556
Finding
Dysostosis multiplex
MedGen UID:
1851010
Concept ID:
C5848292
Disease or Syndrome
Recurrent upper respiratory tract infections
MedGen UID:
154380
Concept ID:
C0581381
Disease or Syndrome
An increased susceptibility to upper respiratory tract infections as manifested by a history of recurrent upper respiratory tract infections (running ears - otitis, sinusitis, pharyngitis, tonsillitis).
Splenomegaly
MedGen UID:
52469
Concept ID:
C0038002
Finding
Abnormal increased size of the spleen.
Reduced tissue alpha-N-acetylglucosaminidase activity
MedGen UID:
1053762
Concept ID:
CN376956
Finding
Concentration or activity of alpha-N-acetylglucosaminidase (EC 3.2.1.50) below the lower limit of normal. This enzyme can be measured in multiple tissues including leukocytes and cultured fibroblasts. It is also known as alpha-acetylglucosaminidase, N-acetyl-alpha-D-glucosaminidase, N-acetyl-alpha-glucosaminidase, and alpha-D-2-acetamido-2-deoxyglucosidase.
Coarse facial features
MedGen UID:
335284
Concept ID:
C1845847
Finding
Absence of fine and sharp appearance of brows, nose, lips, mouth, and chin, usually because of rounded and heavy features or thickened skin with or without thickening of subcutaneous and bony tissues.
Hirsutism
MedGen UID:
42461
Concept ID:
C0019572
Disease or Syndrome
Abnormally increased hair growth referring to a male pattern of body hair (androgenic hair).
Coarse hair
MedGen UID:
124454
Concept ID:
C0277959
Finding
Hair shafts are rough in texture.
Synophrys
MedGen UID:
98132
Concept ID:
C0431447
Congenital Abnormality
Meeting of the medial eyebrows in the midline.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
Follow this link to review classifications for Mucopolysaccharidosis, MPS-III-B in Orphanet.

Professional guidelines

PubMed

Muschol N, Giugliani R, Jones SA, Muenzer J, Smith NJC, Whitley CB, Donnell M, Drake E, Elvidge K, Melton L, O'Neill C; MPS III Guideline Development Group
Orphanet J Rare Dis 2022 Oct 27;17(1):391. doi: 10.1186/s13023-022-02484-6. PMID: 36303195Free PMC Article
Spahiu L, Behluli E, Peterlin B, Nefic H, Hadziselimovic R, Liehr T, Temaj G
Pediatr Endocrinol Diabetes Metab 2021;27(3):201-208. doi: 10.5114/pedm.2021.109270. PMID: 34743503Free PMC Article
Sawamoto K, Álvarez González JV, Piechnik M, Otero FJ, Couce ML, Suzuki Y, Tomatsu S
Int J Mol Sci 2020 Feb 23;21(4) doi: 10.3390/ijms21041517. PMID: 32102177Free PMC Article

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