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Features include always present findings: Postaxial hand polydactyly, Broad thumb, Broad hallux, and Postaxial foot polydactyly; and common findings: Preaxial hand polydactyly, Cutaneous syndactyly of toes, Cutaneous finger syndactyly, and Preaxial foot polydactyly. 19 total HPO annotations.
Data assembled from 6 of 12 sources · Last updated Sep 19, 2026, 11:53 AM UTC
Online Mendelian Inheritance in Man
Genetic and Rare Diseases Info Center
Organ System | Phenotype Count | Example Features |
|---|---|---|
Arms and legs | 6 | Preaxial hand polydactyly, Postaxial hand polydactyly, Cutaneous syndactyly of toes |
Brain and nerves | 2 | Global developmental delay, Intellectual disability |
Skin | 1 | Nail dysplasia |
Growth and development | 1 | Growth delay |
Head and neck | 1 | Macrocephaly |
GLI3-related Greig cephalopolysyndactyly syndrome (GLI3-GCPS) is characterized by macrocephaly, widely spaced eyes associated with increased interpupillary distance, preaxial polydactyly with or without postaxial polydactyly, and cutaneous syndactyly. Less common features include hypoplasia or agenesis of the corpus callosum, developmental delay, intellectual disability, and seizures. To date, approximately 300 individuals with GLI3-GCPS have been reported with a pathogenic variant in GLI3 [Baas et al 2021 (includes individuals with isolated preaxial polydactyly), ]. Frequency of select phenotypic features associated with GLI3-GCPS is based on these reports [, , , , , , , , , , , , , , , , , , , , ]. Table 2. GLI3-Related Greig Cephalopolysyndactyly Syndrome: Frequency of Select Features
Feature | % of Persons w/Feature | Comment |
|---|---|---|
Macrocephaly | 50% | — |
Widely spaced eyes | 50% | — |
Preaxial polydactyly | 90% | More common in the feet |
Markedly broad hallux | 25% | — |
Markedly broad thumb | 30% | — |
Postaxial polydactyly | 50% | More common in the hands |
Cutaneous syndactyly | 75% | Macrocephaly. Occipitofrontal (head) circumference (OFC) is greater than the 97th centile compared to appropriate age- and sex-matched normal standards . |
Source: GeneReviews — "GLI3-Related Greig Cephalopolysyndactyly Syndrome"
GLI3 encodes GLI family zinc finger 3 (1,580 aa). Has a dual function as a transcriptional activator and a repressor of the sonic hedgehog (Shh) pathway, and plays a role in limb development. Highest expression in Uterus (27.0 TPM) and Colon Sigmoid (21.9 TPM).
Polydactyly, postaxial, type A1 is associated with mutations in the GLI3 gene on chromosome 7.
GLI3 is classified as a druggable target (Transcription Factor category) with score 6.5.
Individuals who have GLI3-GCPS associated with a large (300 kb) deletion have a more severe phenotype than those with single-nucleotide variants in GLI3 . Individuals with large deletions appear to have a higher incidence of intellectual disability, seizures, and central nervous system anomalies. This phenomenon is presumably caused by haploinsufficiency of multiple genes in the vicinity of GLI3. Hypoplasia/agenesis of the corpus callosum may be more common in individuals with truncating variants in the 3' end of the gene or individuals with large deletions that encompass GLI3 . Note: GLI3-GCPS has an allelic disorder, GLI3-related Pallister-Hall syndrome (GLI3-PHS). Frameshift variants in GLI3 in the first third of the gene are only known to cause GLI3-GCPS .
Source: GeneReviews — "GLI3-Related Greig Cephalopolysyndactyly Syndrome"
Apparent non-penetrance has been reported . However, it is difficult to estimate the rate of non-penetrance because the genetic status of the parents is often unknown in simplex families (i.e., families in which the proband is the only affected individual).
Source: GeneReviews — "GLI3-Related Greig Cephalopolysyndactyly Syndrome"
No consensus clinical diagnostic criteria for GLI3-related Greig cephalopolysyndactyly syndrome (GLI3-GCPS) have been published.
GLI3-GCPS should be suspected in individuals with the following clinical features and family history.
Clinical features
Macrocephaly
Widely spaced eyes associated with increased interpupillary distance (97th centile)
Preaxial polydactyly with or without postaxial polydactyly
Cutaneous syndactyly
Family history is consistent with autosomal dominant inheritance (e.g., affected males and females in multiple generations). Absence of a known family history does not preclude the diagnosis.
The diagnosis of GLI3-GCPS is established in a proband who has and one of the following identified by molecular genetic testing :
Source: GeneReviews — "GLI3-Related Greig Cephalopolysyndactyly Syndrome"
The differential diagnosis of GLI3-related Greig cephalopolysyndactyly syndrome (GLI3-GCPS) includes genetic disorders characterized by macrocephaly, hypertelorism, and preaxial polydactyly .
Table 4.
Genetic Disorders of Interest in the Differential Diagnosis of GLI3-Related Greig Cephalopolysyndactyly Syndrome
Gene(s) | Disorder | MOI | Clinical Features | Comment
| EFN1B-related craniofrontonasal syndrome (OMIM 304110) | XL1 | • In females: frontonasal dysplasia, craniofacial asymmetry, craniosynostosis, bifid nasal tip, grooved nails, wiry hair, abnormalities of thoracic skeleton
In males: widely spaced eyes
| EFN1B-related craniofrontonasal dysplasia facial features in females are similar to those of GLI3-GCPS.2
Source: GeneReviews — "GLI3-Related Greig Cephalopolysyndactyly Syndrome"
Genetic testing for GLI3 is available. Testing is considered confirmatory for diagnosis.
No approved treatments are currently available for polydactyly, postaxial, type A1. The disease remains an area of unmet medical need.
No clinical practice guidelines for GLI3-related Greig cephalopolysyndactyly syndrome (GLI3-GCPS) have been published. In the absence of published guidelines, the following recommendations are based on the authors' personal experience managing individuals with this disorder.
To establish the extent of disease and needs in an individual diagnosed with GLI3-GCPS, the evaluations summarized (if not performed as part of the evaluation that led to the diagnosis) are recommended.
Table 5.
GLI3-Related Greig Cephalopolysyndactyly Syndrome: Recommended Evaluations Following Initial Diagnosis
System/Concern | Evaluation | Comment
| Measure head circumference. |
| Examine for limb anomalies. | Incl radiographs to assess extent of limb anomalies
Orthopedic eval |
OT/ developmental eval | Determine any functional limitations that would benefit from therapy.
| Developmental assessment | • To incl motor, adaptive, cognitive, speech-language eval
Eval for early intervention/ special education as needed
| Neurologic eval | • EEG if seizures are a concern.
Consider brain imaging if significant developmental delays are present.
| By genetics professionals1 | To obtain a pedigree inform affected persons their families re nature, MOI, implications of GLI3-GCPS to facilitate medical personal decision making
Source: GeneReviews — "GLI3-Related Greig Cephalopolysyndactyly Syndrome"
As is true for any malformation of the feet, surgical correction must be carefully considered. Cosmetic benefits and easier fitting of shoes can be outweighed by potential orthopedic complications.
Source: GeneReviews — "GLI3-Related Greig Cephalopolysyndactyly Syndrome"
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 — "GLI3-Related Greig Cephalopolysyndactyly Syndrome"
View trials for polydactyly, postaxial, type A1
To monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations, the evaluations summarized in are recommended. Table 7. GLI3-Related Greig Cephalopolysyndactyly Syndrome: Recommended Surveillance
System/Concern | Evaluation | Frequency |
|---|---|---|
Macrocephaly | Assess rate of head growth; if faster than normal or if neurologic concerns arise, brain MRI is indicated. | At each visit or at least annually during infancy childhood |
Limb anomalies | Physical medicine OT/PT assessment of mobility self-help skills | At each visit or as needed Development |
Seizures | Monitor those w/seizures as clinically indicated. | At each visit OT = occupational therapy; PT = physical therapy |
Source: GeneReviews — "GLI3-Related Greig Cephalopolysyndactyly Syndrome"
Phenotype severity distribution: 4 always present features, 4 common features.
No clinical trials have been registered for polydactyly, postaxial, type A1.
20 publications have been identified in PubMed for polydactyly, postaxial, type A1. Research spans Case Report / Case Series (45%), Basic Science / Preclinical (20%), and Clinical Trial Publication (15%).
Research Type | Count | % of Total |
|---|---|---|
Patient case studies | 9 | 45% |
Laboratory research | 4 | 20% |
Clinical study results | 3 | 15% |
Research summaries | 2 | 10% |
Other research | 1 | 5% |
Disease patterns and progression | 1 | 5% |
Gomes A (2026). [PMID: 40799178](https://pubmed.ncbi.nlm.nih.gov/40799178/). *Am J Med Genet A*. [Case Report / Case Series]
Zeniya T (2026). [PMID: 41238473](https://pubmed.ncbi.nlm.nih.gov/41238473/). *J Orthop Sci*. [Clinical Trial Publication]
Mendenhall SD (2026). [PMID: 40489747](https://pubmed.ncbi.nlm.nih.gov/40489747/). *Plast Reconstr Surg*. [Epidemiology / Natural History]
Wang L (2026). [PMID: 41703510](https://pubmed.ncbi.nlm.nih.gov/41703510/). *BMC Ophthalmol*. [Case Report / Case Series]
Qi Y (2025). [PMID: 40052367](https://pubmed.ncbi.nlm.nih.gov/40052367/). *Mol Genet Genomic Med*. [Basic Science / Preclinical]
Cordray H (2025). [PMID: 40048375](https://pubmed.ncbi.nlm.nih.gov/40048375/). *Plast Reconstr Surg*. [Clinical Trial Publication]
Njie R (2025). [PMID: 40857061](https://pubmed.ncbi.nlm.nih.gov/40857061/). *J Cell Mol Med*. [Review / Meta-Analysis]
Liao W (2025). [PMID: 41388393](https://pubmed.ncbi.nlm.nih.gov/41388393/). *BMC Musculoskelet Disord*. [Clinical Trial Publication]
Abdullah (2025). [PMID: 41010063](https://pubmed.ncbi.nlm.nih.gov/41010063/). *Genes (Basel)*. [Basic Science / Preclinical]
Morcos M (2025). [PMID: 40085725](https://pubmed.ncbi.nlm.nih.gov/40085725/). *JBJS Case Connect*. [Case Report / Case Series]