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A rare genetic syndrome with an autosomal recessive pattern of inheritance. It is caused by a mutation in the ESCO2 gene. Clinical signs at birth include multiple limb and facial abnormalities.
Features include always present findings: Phocomelia and Underdeveloped nasal alae; and very common findings: Microcephaly, Hyperplasia of the maxilla, and Absent radius. 72 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Head and neck | 7 | Cavernous hemangioma of the face, Microcephaly, Cleft palate |
Muscles | 4 | Knee flexion contracture, Ankle flexion contracture, Elbow flexion contracture |
Eyes | 3 | Opacification of the corneal stroma, Cloudy or opaque cornea (corneal opacity), Cataract |
Brain and nerves | 3 | Cranial nerve paralysis, Hydrocephalus, Intellectual disability |
Kidneys and urinary system | 2 | Horseshoe kidney, Polycystic kidney dysplasia |
Arms and legs | 2 | Finger aplasia, Radial deviation of finger |
Growth and development | 2 | Postnatal growth retardation, Severe intrauterine growth retardation |
Heart and blood vessels | 2 | Ventricular septal defect, Atrial septal defect |
Digestive system | 2 | Accessory spleen, Biliary tract abnormality |
ESCO2 spectrum disorder is characterized by mild-to-severe prenatal growth restriction, limb malformations (which can include bilateral symmetric tetraphocomelia or hypomelia caused by mesomelic shortening), hand anomalies, multiple joint contractures, craniofacial abnormalities, and often ocular manifestations. Intellectual disability is common. To date, 173 individuals have been identified with ESCO2 spectrum disorder. The following description of the phenotypic features associated with this condition is based on these reports . Table 2. ESCO2 Spectrum Disorder: Frequency of Select Clinical Features
Feature | % of Individuals w/Feature | Comment |
|---|---|---|
Growth deficiency | 95% | — |
Phocomelia | 95% | Upper limbs only (21%) |
Upper lower limbs (79%) Microcephaly | 81% | — |
Bone fusions | 65% | Knees, ankles, wrists, elbows, talipes equinovarus; Syndactyly (18%) |
Flexion contractures (16%) Cleft lip palate | 47% | Cleft palate only (5%) |
Ocular abnormalities | 37% | Microphthalmia (48%), nystagmus (48%), glaucoma (48%), corneal opacities (22%) |
Developmental delay/ intellectual disability | 37% | — |
Urogenital anomalies | 27% | Enlarged phallus/clitoris (20%) |
Cryptorchidism (13%) Cardiac anomalies | 20% | ASD, VSD, PDA |
Kidney anomalies | 12% | Polycystic kidney, horseshoe kidney Growth restriction of prenatal onset is the most consistent finding in all affected individuals. Postnatal growth restriction can be moderate to severe and correlates with the severity of the limb and craniofacial malformations. |
Source: GeneReviews — "ESCO2 Spectrum Disorder"
ESCO2 encodes establishment of sister chromatid cohesion N-acetyltransferase 2 (601 aa). Acetyltransferase required for the establishment of sister chromatid cohesion. Couples the processes of cohesion and DNA replication to ensure that only sister chromatids become paired together. Highest expression in Cells EBV-transformed lymphocytes (17.0 TPM) and Testis (4.6 TPM).
Roberts-SC phocomelia syndrome is caused by mutations in the ESCO2 gene on chromosome 8.
The ESCO2 protein participates in Acetylation of SMC3 subunit of centromeric chromatin associated cohesin by ESCO1 or ESCO2, Acetylation of SMC3 subunit of chromosomal arm associated cohesin by ESCO1 or ESCO2, and CDCA5 (Sororin) enables cohesion of sister chromosomal arms pathways.
ESCO2 is classified as a druggable target with score 0.0.
To date, correlation of ESCO2 pathogenic variants with specific phenotypic features has not been established.
Source: GeneReviews — "ESCO2 Spectrum Disorder"
ESCO2 spectrum disorder comprises a phenotypic continuum that ranges from Roberts syndrome at the severe end to SC phocomelia syndrome at the milder end.
ESCO2 spectrum disorder should be suspected in an individual with the following clinical findings and family history. Clinical findings
Source: GeneReviews — "ESCO2 Spectrum Disorder"
While some syndromes share some of the clinical features of ESCO2 spectrum disorder, a physical examination and skeletal survey should allow for differentiation between individuals with ESCO2 spectrum disorder and those with genetic or acquired conditions that are clinically similar. Table 3. Genes of Interest in the Differential Diagnosis of ESCO2 Spectrum Disorder
Gene(s) | Disorder | MOI | Limb Malformations | Other Clinical Features | Comment |
|---|---|---|---|---|---|
Fanconi anemia | ARADXL1 | Unilateral or bilateral malformations of upper limbs (e.g., hypoplastic thumb hypoplastic radius) lower limbs | Bone marrow failure, risk for malignancy; Physical abnormalities (e.g., short stature, abnormal skin pigmentation, microcephaly, ophthalmic genitourinary tract anomalies) | Disorder w/preaxial reduction defects to consider in persons w/mild manifestations BRD4 HDAC8 NIPBL RAD21 SMC1A | — |
Genetic testing for ESCO2 is available. Testing is considered confirmatory for diagnosis.
No approved treatments are currently available for Roberts-SC phocomelia syndrome. The disease remains an area of unmet medical need.
No clinical practice guidelines for ESCO2 spectrum disorder have been published. In the absence of published guidelines, the following recommendations are based on the literature, the experience of clinical geneticists, and authors' personal experience managing individuals with this disorder.
To establish the extent of disease and needs in an individual diagnosed with ESCO2 spectrum disorder the evaluations summarized (if not performed as part of the evaluation that led to the diagnosis) are recommended.
Table 4.
ESCO2 Spectrum Disorder: Recommended Evaluations Following Initial Diagnosis
System/Concern | Evaluation | Comment
| Measure height, weight, head circumference. | Assess for evidence of poor weight gain growth deficiency.
| Multidisciplinary clinic assessment by orthopedist, physical medicine specialist, OT, PT | Assess:
Gross motor fine motor skills, contractures;
Need for adaptive devices to improve fine motor gross motor skills;
Possible need for surgery to improve prehensile hand grasp /or prostheses.
| Multidisciplinary craniofacial team assessment | Assess:
Effect of lip palatal anomalies on feeding speech development;
Need for surgical interventions.
| Assessment by pediatric ophthalmologist | • Newborn: corneal opacities
Adolescence early adulthood: cranial nerve III cavernous angioma
Developmental delay/
| Developmental assessment | To incl:
Source: GeneReviews — "ESCO2 Spectrum Disorder"
Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.
Source: GeneReviews — "ESCO2 Spectrum Disorder"
View trials for Roberts-SC phocomelia syndrome
To monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations, the evaluations summarized in are recommended. Table 6. ESCO2 Spectrum Disorder: Recommended Surveillance
System/Concern | Evaluation | Frequency |
|---|---|---|
Growth | Assess growth incl weight, height, head circumference. | At every visit |
Kidney anomalies | Blood pressure measurement | At each visit Kidney function tests |
Eye abnormalities | Visual acuity | Per treating ophthalmologist |
Congenital heart defects | Per treating cardiologist/ cardiac surgeon | Per treating cardiologist/ cardiac surgeon |
Malignancies | Physical exam incl full skin exam neurologic exam for evidence of malignancy | Annually |
Stroke | Referral to neurologist incl brain imaging for vascular anomalies aneurysms | In those w/ID, corneal opacities, /or heart defects Assess for clinical manifestations of aneurysms vascular malformations. |
Source: GeneReviews — "ESCO2 Spectrum Disorder"
Phenotype severity distribution: 2 always present features, 3 very common features, 8 common features.
Estimated prevalence: Unknown (Unknown prevalence).
No clinical trials have been registered for Roberts-SC phocomelia syndrome.
14 publications have been identified in PubMed for Roberts-SC phocomelia syndrome. Research spans Basic Science / Preclinical (46%), Case Report / Case Series (23%), and Other (15%).
Research Type | Count | % of Total |
|---|---|---|
Laboratory research | 6 | 46% |
Patient case studies | 3 | 23% |
Other research | 2 | 15% |
Research summaries | 2 | 15% |
Liu Y (2026). [PMID: 42103099](https://pubmed.ncbi.nlm.nih.gov/42103099/). *J Genet Genomics*. [Review / Meta-Analysis]
Sanchez AC (2026). [PMID: 40396618](https://pubmed.ncbi.nlm.nih.gov/40396618/). *Dev Dyn*. [Basic Science / Preclinical]
Bharuka A (2025). [PMID: 40635816](https://pubmed.ncbi.nlm.nih.gov/40635816/). *J Anaesthesiol Clin Pharmacol*. [Other]
Sulaiman SA (2025). [PMID: 41255663](https://pubmed.ncbi.nlm.nih.gov/41255663/). *World J Clin Pediatr*. [Case Report / Case Series]
Leduc F (2025). [PMID: 40673520](https://pubmed.ncbi.nlm.nih.gov/40673520/). *Clin Genet*. [Review / Meta-Analysis]
Duke G (2025). [PMID: 40492837](https://pubmed.ncbi.nlm.nih.gov/40492837/). *Genetics*. [Basic Science / Preclinical]
Nerakh G (2025). [PMID: 40657982](https://pubmed.ncbi.nlm.nih.gov/40657982/). *Clin Dysmorphol*. [Case Report / Case Series]
Begum A (2025). [PMID: 40912730](https://pubmed.ncbi.nlm.nih.gov/40912730/). *BMJ Case Rep*. [Case Report / Case Series]
Marathe S (2025). [PMID: 40668332](https://pubmed.ncbi.nlm.nih.gov/40668332/). *Protein J*. [Basic Science / Preclinical]
Singh G (2025). [PMID: 41341165](https://pubmed.ncbi.nlm.nih.gov/41341165/). *bioRxiv*. [Basic Science / Preclinical]
Data assembled from 8 of 12 sources · Last updated Sep 19, 2026, 6:55 PM UTC
Online Mendelian Inheritance in Man
European rare disease database
Genetic and Rare Diseases Info Center
Common questions about Roberts-SC phocomelia syndrome
SMC3 |
Cornelia de Lange syndrome (CdLS) |
ADXL2 |
Upper-limb reduction defects ranging from subtle phalangeal abnormalities to oligodactyly |
Distinctive craniofacial features,3 growth restriction (prenatal onset, 5th centile throughout life), hirsutism, cardiac septal defects, gastrointestinal dysfunction, hearing loss, myopia, cryptorchidism or hypoplastic genitalia |
Cytogenetic findings: PCS/HR in ESCO2 spectrum disorder is different from PSCS in CdLS, in which separation splaying involves not only centromeric regions but also entire sister chromatids.4 BUB1B CENATAC CEP57 MAD1L1 |
TRIP13 | Mosaic variegated aneuploidy syndrome (OMIM PS257300) | AR | Severe microcephaly, growth restriction, ID; Childhood cancer predisposition; Cytogenetic findings: PCS/HR in ESCO2 spectrum disorder is different from PCD in mosaic variegated aneuploidy syndrome, in which separation splaying involves not only centromeric regions but also entire sister chromatids. | — | — |
Thrombocytopenia-absent radius (TAR) syndrome | AR | Bilateral absence of radii w/presence of both thumbs, plus other upper- lower-limb skeletal anomalies | Generally transient thrombocytopenia (50 platelets/nL); Anomalies of vertebrae, heart, genitourinary system; Cleft lip palate assoc w/skeletal changes such as absent radius suggests ESCO2 spectrum disorder rather than TAR syndrome. | — | — |
RECQL4 | Baller-Gerold syndrome6 | AR | Radial ray defect manifesting as oligodactyly; aplasia or hypoplasia of thumb /or of radius | — | — |
Patellar hypo- or aplasia becomes apparent in childhood. | Coronal craniosynostosis (brachycephaly) w/ocular proptosis prominent forehead, growth restriction, poikiloderma | Disorder w/preaxial r... | — | — | — |
Source: GeneReviews — "ESCO2 Spectrum Disorder"