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A genetic disorder characterized by abnormalities in the breakdown of phytanic acid. It results in accumulation of phytanic acid in the blood, brain and other tissues. Signs and symptoms include retinitis pigmentosa which may lead to blindness, hearing problems and deafness, hypotonia, ataxia, nystagmus, facial deformities, and mental and growth retardation.
Features include always present findings: Low muscle tone (hypotonia), Ataxia, Abnormal light-adapted flicker electroretinogram, and Nystagmus and others. 30 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Brain and nerves | 7 | Polyneuropathy, Ataxia, Depressed nasal ridge |
PEX12 function has not been fully characterized.
Peroxisome biogenesis disorder type 3B is associated with mutations in the PEX12 gene on chromosome 17.
A general relationship appears to exist among the genotype, cellular phenotype (i.e., import of peroxisomal matrix proteins), and clinical phenotype . PEX gene defects are associated with loss-of-function variants; hence, variants that abolish activity (e.g., large deletions, nonsense, frameshift variants) are most severe. In contrast, missense variants that retain some residual function have a less severe effect on peroxisome assembly; however, it should be noted that not all missense variants have residual activity. Due to the overall rarity of ZSD the opportunities to rigorously assess genotype and phenotype are limited.
Suggestive Findings Zellweger spectrum disorder (ZSD) should be suspected in children with the following and findings. Clinical Findings In newborns: • Hypotonia • Poor feeding • Distinctive facies • Brain malformations • Seizures • Renal cysts • Hepatomegaly, cholestasis, and hepatic dysfunction • Bony stippling (chondrodysplasia punctata) of the patella(e) and other long bones In older infants and children: • Developmental delays with or without hypotonia (Note: Intellect can be normal.) • Failure to thrive • Hearing loss • Vision impairment • Liver dysfunction • Adrenal dysfunction • Leukodystrophy • Peripheral neuropathy and ataxia Laboratory Findings The screening assays for ZSD are summarized in . Note that because some individuals with ZSD do not have abnormalities of these screening assays in body fluids or cultured cells, molecular genetic testing is necessary to establish the diagnosis . Functional testing in fibroblasts remains an ancillary tool to confirm equivocal molecular and/or biochemical results. Table 1. Screening Assays for Zellweger Spectrum Disorder
No approved treatments are currently available for peroxisome biogenesis disorder type 3B. The disease remains an area of unmet medical need.
(full text) and (full text) have published management and treatment guidelines for Zellweger spectrum disorder (ZSD). Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with ZSD, the evaluations summarized (if not performed as part of the evaluation that led to the diagnosis) are recommended. Table 5. Recommended Evaluations Following Initial Diagnosis in Individuals with Zellweger Spectrum Disorder
Table 7. Recommended Surveillance for Individuals with Zellweger Spectrum Disorder
System/Concern |
|---|
No clinical trials have been registered for peroxisome biogenesis disorder type 3B.
2 publications have been identified in PubMed for peroxisome biogenesis disorder type 3B. Research spans Case Report / Case Series (100%).
Su J (2026). [PMID: 41495707](https://pubmed.ncbi.nlm.nih.gov/41495707/). *BMC Pediatr*. [Case Report / Case Series]
Khalilian S (2025). [PMID: 40205409](https://pubmed.ncbi.nlm.nih.gov/40205409/). *BMC Med Genomics*. [Case Report / Case Series]
Data assembled from 6 of 12 sources · Last updated Sep 19, 2026, 9:40 PM UTC
Online Mendelian Inheritance in Man
Genetic and Rare Diseases Info Center
2 |
Low muscle tone (hypotonia), Generalized hypotonia |
Head and neck | 2 | Flat face, Abnormal facial shape |
Eyes | 2 | Nystagmus, Retinal dystrophy |
Blood and immune system | 1 | Abnormal bleeding tendency (abnormal bleeding) |
Digestive system | 1 | Enlarged liver (hepatomegaly) |
Bones and joints | 1 | Weak and brittle bones (osteoporosis) |
Growth and development | 1 | Failure to thrive |
Lab test results | 1 | Elevated circulating phytanic acid concentration |
Ears | 1 | Inner ear hearing loss (sensorineural hearing impairment) |
Zellweger spectrum disorder (ZSD) is defined by a continuum of three phenotypes described before the biochemical and molecular bases of these disorders had been fully determined: Zellweger syndrome (ZS), neonatal adrenoleukodystrophy (NALD), and infantile Refsum disease (IRD) . The ZSD phenotypic spectrum is broad; some affected individuals have mild manifestations, mainly sensory deficits and/or mild developmental delay. Recently, individuals with normal intellect have been identified by genomic testing methods. Nonetheless, all of the peroxisome assembly disorders cause significant morbidity, frequently resulting in death in childhood.
Source: GeneReviews — "Zellweger Spectrum Disorder"
Source: GeneReviews — "Zellweger Spectrum Disorder"
Compound | Test | Expected Findings | Limitations of Test |
|---|---|---|---|
C26:0 LPC1 | Dried blood spot concentrations | C26:0-LPC concentrations | Persons w/mild ZSD may not be detected. |
VLCFA | Plasma concentration | plasma concentrations of C26:0 C26:1; ratios of C24/C22 C26/C222 | Non-fasting samples, hemolyzed samples, or a person on a ketogenic diet can cause false positive results. |
Phytanic acid pristanic acid3 | Plasma concentration | concentrations of phytanic acid /or pristanic acid | Branched-chain fatty acid accumulation depends on dietary intake of phytanic acid, which is minimal in formula- breast-fed infants. Thus, phytanic pristanic acid levels are normal in a neonate w/ZSD. |
Plasmalogens | Erythrocyte membrane concentrations | amounts of C16 C18 plasmalogens | Persons w/moderate-to-mild ZSD may have marginally-to-normal plasmalogen levels. |
Pipecolic acid | Plasma/urine concentration | concentration of pipecolic acid in both plasma urine | Urinary excretion of pipecolic acid is high in neonatal period but diminishes w/age.4 Thus, urine should be tested in a neonate plasma in an older child or adult. |
Bile acids | Plasma/urine concentration | concentrations of C27 bile acid intermediates THCA DHCA | In most cases plasma testing is more sensitive than urine analysis. |
Source: GeneReviews — "Zellweger Spectrum Disorder"
The differential diagnosis of Zellweger spectrum disorder (ZSD) varies with age at presentation and most prominent feature of the presentation. ZSD in newborns is most often confused with other conditions that result in profound hypotonia including Down syndrome, other chromosome abnormalities, and the disorders summarized in . Table 3. Differential Diagnosis of ZSD in a Newborn with Profound Hypotonia
Gene(s)/ Genetic Mechanism | Disorder | MOI |
|---|---|---|
DMPK | Congenital myotonic dystrophy type 1 | AD MTM1 |
SELENON | Multiminicore disease (OMIM 255320, 602771) | AR SMN1 |
Differential Diagnosis of ZSD – Other Peroxisomal Disorders Gene | Disorder | MOI |
ABCD1 | XL adrenoleukodystrophy1 | XL |
Source: GeneReviews — "Zellweger Spectrum Disorder"
Genetic testing for PEX12 is available. Testing is considered confirmatory for diagnosis.
System/Concern | Evaluation | Comment |
|---|---|---|
Feeding | Feeding nutrition assessment | To incl eval of aspiration risk nutritional status; Consider eval for gastrostomy tube placement in those w/dysphagia /or aspiration risk. |
Hearing | Audiologic eval | Assess for hearing loss. |
Eyes | Comprehensive ophthalmologic assessment | OCT exam in adherent patients has shown cystoid macular edema . Hepatic |
Neurologic | Neurologic eval | To incl brain MRI; Consider EEG if seizures are a concern. |
Development | Developmental assessment | To incl motor, adaptive, cognitive, speech-language eval; Eval for early intervention/ special education Endocrine |
Renal | Urine oxalate-to-creatinine ratio, serial kidney ultrasound (can be done w/liver ultrasounds) | Some affected persons develop urolithiasis nephrocalcinosis assoc w/urinary oxalate load . |
Dental | Dental eval | Ameliogenesis imperfects, typically of secondary teeth, requires extensive dental interventions. Genetic |
counseling | By genetics professionals1 | To obtain a pedigree inform affected persons families re nature, MOI, implications of ZSD in order to facilitate medical personal decision making Family support resources |
Treatment of Manifestations in Individuals with Zellweger Spectrum Disorder Manifestation/Concern | Treatment | Considerations/Other Feeding nutrition |
Hearing | Hearing aids in children found to have hearing impairment | See also Genetic Hearing Loss Overview for discussion of management issues. Vision impairment |
Seizures | Standard treatment w/ASM by experienced neurologist | No type of ASM is contraindicated. Seizures may be difficult to control despite use of appropriate medication. |
DD/ID | Provide early-intervention services. | Adrenal |
insufficiency | Adrenal replacement therapy | Osteopenia |
imperfecta | Treatment per dentist | , Renal oxalate |
stones | Supportive treatment has included hydration, lithotripsy, surgical intervention. | Pyridoxine treatment did not oxalate excretion in 1 study . |
Vaccination | Annual influenza respiratory syncytial virus vaccines as well as usual vaccination schedule | ASM = anti-seizure medication; DD = developmental delay; ID = intellectual disability 1. |
Source: GeneReviews — "Zellweger Spectrum Disorder"
Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.
Source: GeneReviews — "Zellweger Spectrum Disorder"
View trials for peroxisome biogenesis disorder type 3B
Evaluation
Frequency |
|---|
Hearing | Audiology eval | Annually Eyes |
Neurologic | Monitor those w/seizures as clinically indicated. | At each visit Head MRI to evaluate for white matter changes that may explain changes in cognitive /or motor ability |
Development | Monitor developmental progress educational needs. | At each visit |
Endocrine | Assess adrenal function (ACTH cortisol). | By age 1 yr; annually thereafter |
Dental | Dental exam | Every 6 mos after dental eruption Renal stones |
Other | Assess family need for social work support (e.g., palliative/respite care, home nursing, other local resources) care coordination. | At each visit |
Source: GeneReviews — "Zellweger Spectrum Disorder"
Phenotype severity distribution: 12 always present features.