Polysyndactyly and Limb Malformations in a Newborn with Mohr Syndrome (OFD Type II): A Rare Orthopedic Perspective

Abstract

Background:
Mohr syndrome (Oral-Facial-Digital Syndrome type II) is a rare, autosomal recessive condition marked by craniofacial, oral, digital, and sometimes central nervous system and cardiac anomalies. Among these, digital anomalies such as polydactyly and syndactyly are of orthopedic significance due to their potential impact on function and quality of life.

Clinical case:
We report a full-term male newborn, first in birth order of non-consanguineous parents, who presented with respiratory distress and multiple congenital anomalies. Notable features included median cleft lip, hairy forehead, ocular hypertelorism, broad nasal root, and bilateral polysyndactyly of both hands and feet with hallucial duplication. Systemic evaluation revealed Double Outlet Right Atrium (DORA) and Dandy-Walker malformation. A clinical diagnosis of Mohr syndrome was made based on phenotypic presentation in the absence of genetic testing. The limb anomalies are consistent with orthopedic features reported in Mohr syndrome.

Discussion:
The presence of bilateral postaxial and preaxial polydactyly, particularly with duplication of halluces and hand anomalies, is highly suggestive of OFD type II and differentiates it from OFD type I. Early recognition of these musculoskeletal features enables timely orthopedic consultation. Literature review supports early surgical planning to prevent functional impairment in cases of syndromic polydactyly.

Conclusion:
Mohr syndrome should be considered in neonates presenting with combined craniofacial and limb anomalies. Early orthopedic evaluation is crucial for functional planning, and multidisciplinary management is key for long-term outcomes.

Full Text

Background
Mohr syndrome, or Oral-Facial-Digital Syndrome type II (OFDS II), is a rare autosomal recessive disorder characterized by craniofacial anomalies, oral clefts, and digital malformations including polydactyly and syndactyly. Fewer than 20 cases have been reported globally, highlighting the rarity of this condition and the need to document phenotypic variability to aid early recognition and diagnosis.¹

Orthopedic manifestations, particularly bilateral polysyndactyly and duplication of halluces are central diagnostic features and may present functional limitations if not addressed early.^2,3 Timely identification of such malformations enables early surgical planning, which is essential for optimizing limb function and minimizing developmental delays.

This case is important as it demonstrates the classical limb anomalies associated with Mohr syndrome in the context of a low-resource setting where genetic testing is unavailable. It reinforces the critical role of orthopedic assessment in syndromic neonates and contributes to clinical awareness for prompt multidisciplinary intervention.

Clinical case

Anamnesis

A full-term male neonate, the first child of non-consanguineous healthy parents of Asian descent, was delivered via spontaneous vaginal delivery at 39 weeks of gestation in a secondary-level hospital. Birth weight was 3.6 kg, and the baby cried immediately after birth. Within the first hour of life, the neonate developed respiratory distress and was noted to have multiple congenital anomalies. The newborn was transferred to the neonatal intensive care unit (NICU) for further evaluation.

There was no significant maternal illness during pregnancy, and antenatal ultrasounds were unremarkable. There was no history of teratogen exposure or similar congenital anomalies in the family. Both parents denied any history of consanguinity or inherited disorders.
On initial examination, the baby had facial dysmorphism: a median cleft lip, hairy forehead, ocular hypertelorism, a broad nasal bridge, and transverse palpebral fissures (Fig. 3). Limb anomalies included bilateral polysyndactyly of the hands with duplication of the thumbs, and bilateral duplication of the great toes with postaxial polydactyly and syndactyly of both feet (Fig. 1, Fig. 2 and Fig. 3). There were no signs of hypotonia or scoliosis. Cardiovascular examination suggested a congenital heart defect.

Diagnostic assessment

Diagnostic procedures and findings are outlined chronologically below:

Date	Investigation	Findings
Day 1 (Birth)	Physical examination	Facial dysmorphism, bilateral hand and foot polysyndactyly, cleft lip, respiratory distress
Day 1	Chest auscultation	Pan-systolic murmur heard at left lower sternal border
Day 2	Echocardiography	Double Outlet Right Atrium (DORA)
Day 2	Brain ultrasonography	Dandy-Walker malformation with cystic dilation of fourth ventricle and hypoplasia of cerebellar vermis
Day 3	Routine blood work	Within normal limits (CBC, electrolytes, blood sugar)
Day 4	ENT and ophthalmology screening	No significant abnormalities detected
Not performed	Genetic testing/Karyotyping	Not available due to resource limitations

Radiographs of the hands and feet were not obtained immediately due to clinical stability priorities, but were planned for outpatient follow-up.

The differential diagnosis

The presence of orofacial clefting, hairy forehead, and polysyndactyly suggested a syndromic diagnosis. The initial differential included:

1. Oral-Facial-Digital Syndrome Type I (OFD I) - excluded due to male sex (OFD I is X-linked dominant, typically lethal in males), absence of polycystic kidneys, and absence of corpus callosum agenesis.

2. Ellis-van Creveld syndrome - excluded due to absence of short stature, nail dysplasia, and normal chest size.

3. Bardet-Biedl syndrome - excluded due to absence of obesity, retinal dystrophy, renal anomalies, and developmental delay at birth.

Based on phenotypic presentation and absence of features pointing to alternate syndromes, a clinical diagnosis of Oral-Facial-Digital Syndrome type II (Mohr Syndrome) was established.

Interventions

Initial supportive care in NICU included:

• Oxygen therapy via nasal prongs at 1 L/min for 48 hours.
• Breastfeeding with nasogastric support in the initial 2 days due to mild respiratory difficulty.
• Multidisciplinary consultation: Pediatric cardiology and neurology were consulted based on DORA and Dandy-Walker malformation findings.

No pharmacological treatment or surgical intervention was initiated during the hospital stay. Orthopedic and plastic surgery consultations were planned for outpatient follow-up to assess limb malformation and future reconstructive needs.

Follow-up and outcomes

The baby stabilized and was discharged on day 7 of life with normal vital signs and no ongoing respiratory support. Parents were counseled extensively regarding:

• Multisystem involvement of Mohr syndrome.
• The need for early imaging of limbs for surgical planning (e.g., excision of nonfunctional digits, syndactyly release).
• Follow-up with pediatric cardiology for DORA.
• Neurology review for Dandy-Walker malformation and developmental monitoring.

The patient was lost to follow-up after discharge. Despite multiple attempts at telephonic contact, the family did not return for outpatient review, reportedly due to relocation to a remote region with limited medical access.

Discussion

At-least 14 types of OFDS had been identified and upto OFD type XVIII has been listed in the OMIM database.4 Less than 20 cases of Mohr syndrome have been reported so far and the prevalence is less than 1/1000000.⁵

This case of a neonate with Mohr syndrome (OFD type II) illustrates a classic presentation of this rare syndrome, marked by the co-occurrence of orofacial anomalies, digital malformations, and central nervous system and cardiac defects. The phenotypic features including bilateral polysyndactyly with duplication of halluces and thumbs, cleft lip, and Dandy-Walker malformation strongly support the clinical diagnosis in the absence of genetic confirmation.

A major strength of this report lies in the detailed documentation of orthopedic manifestations at birth, which are diagnostic cornerstones in syndromic cases such as OFDS II. Early orthopedic involvement is vital, as limb malformations like synpolydactyly can impair grasp, ambulation, and neurodevelopmental milestones. Literature supports early planning of surgical correction of supernumerary digits and syndactyly release to optimize hand and foot function.^2,3

The presence of Double Outlet Right Atrium (DORA) adds to the diagnostic weight and also highlights the complexity of associated congenital heart anomalies in Mohr syndrome. While most reported cardiac defects include atrioventricular canal defects or septal defects,6 this case broadens the cardiac phenotype spectrum.

Limitations include the lack of confirmatory genetic testing and post-discharge follow-up, which hindered the ability to perform radiographic assessment and monitor neurodevelopmental and functional outcomes. Additionally, limited resources restricted a full multidisciplinary evaluation during hospitalization.

This case contributes to the literature by highlighting the orthopedic relevance of syndromic polydactyly in early diagnosis and long-term planning. While Mohr syndrome remains rare, its consistent phenotypic expression in the limbs allows for early identification, even in resource-limited settings. Generalization to a broader population must be done cautiously due to the rarity of the syndrome, but the approach demonstrated clinical pattern recognition and targeted specialist involvement remains universally applicable.

Conclusion

This case underscores the clinical significance of recognizing Mohr syndrome early, especially through its orthopedic manifestations. While definitive genetic diagnosis was not available, the classical combination of craniofacial and digital anomalies enabled a clinical diagnosis. Based on this case, the following key points are emphasized:

• Bilateral polydactyly with hallux duplication is a hallmark feature of Mohr syndrome and should prompt clinicians to consider syndromic diagnoses.
• Early orthopedic assessment in syndromic neonates is essential for planning surgical interventions to optimize function and development.
• Clinical diagnosis remains crucial in resource-limited settings where genetic testing is unavailable, especially when phenotypic features are distinctive.
• Multisystem evaluation including cardiology and neurology is necessary, as Mohr syndrome often presents with congenital heart and central nervous system anomalies.
• Parental counseling and multidisciplinary follow-up are vital for prognosis and coordination of long-term care.

Figures

Fig. 1. Polydactyly in the right hand in a case of Mohr syndrome

Fig. 2. Synpolydactyly in the right hand in a case of Mohr syndrome

Fig. 3. Hairy forehead, transverse slanting of palpebral fissures, broad nasal root and cleft lip in the case of Mohr syndrome

Fig. 4. Synpolydactyly in the right foot in the case of Mohr syndrome