Adducted Thumbs Syndrome

At a glance

Disorder with bilateral adducted thumbs, craniosynostosis, microcephaly, muscular hypotonia, most often mental delay, and respiratory issues.

Synonyms

Christian Syndrome I; Christian-Andrews-Conneally-Muller Syndrome.

Incidence

Approximately 10 cases have been reported. Three of the four initially reported cases occurred in an Amish community and were the products of consanguineous parents who could be traced to a single pair of common ancestors.

Genetic inheritance

Inheritance seems to be autosomal recessive. Adducted thumbs can be part of numerous other conditions (see below).

Diagnosis

Based on the clinical findings and family history.

Clinical aspects

The most characteristic sign is flexion and adduction of the thumbs with Arthrogryposis of elbows, wrists, and knees. Other typical features include craniosynostosis with ridged cranial sutures, microcephaly, a prominent occiput, mental retardation, generalized seizures, apneas, asymmetric facial weakness (described as stiffness), downslanting of the palpebral fissures, telecanthus, external ophthalmoplegia, low-set, malformed and posteriorly rotated ears, micrognathia, high-arched palate with cleft palate and/or uvula, and velopharyngeal insufficiency. Swallowing difficulties with esophageal dysmotility, laryngomalacia, and difficulties clearing tracheobronchial secretions as well as generalized myopathic hypotonia are at least in part responsible for the feeding difficulties with failure to thrive and recurrent aspirations with pneumonias leading to respiratory insufficiency, which was the main cause of death in early infancy (only two patients has survived the first year of life). Other common findings include pectus excavatum, short first metacarpals, dislocated hips, and clubfeet. Localized hypertrichosis and abnormal dermatoglyphic patterns were described in some patients and a ventricular septal defect (most likely, report is unclear) in one. The neurohistopathologic analysis (in one patient) revealed dysmyelination of a previously undescribed type with solubilization of formed myelin followed by calcium-complexing and redeposition. Extensive glial proliferation was noted in the white matter of the posterior column of the spinal cord, but also widely distributed in brainstem, cerebrum, and cerebellum. Myelination of peripheral nerves was considered appropriate. Hypo- or areflexia was noted in some patients. A muscle biopsy revealed unspecific signs of congenital myopathy with great variation in fiber size, but normal proportions of Type I and Type II fibers. There was an increase in interstitial tissue and the number of centrally located nuclei, but no dystrophic changes, denervation patterns, or structural anomalies could be detected. Electromyography was done in three patients and showed fibrillations in some muscles.

Precautions before anesthesia

Obtain a history of developmental milestones, apneas, muscular hypotonia, recent chest infections, and swallowing difficulties. Assess respiratory function and obtain a chest x-ray as required. Arterial blood gas analysis may be helpful under certain circumstances. Postoperative mechanical ventilation may be needed given the poor muscle function and associated respiratory problems (ie, apneas, aspirations, pneumonia, laryngomalacia). Anticonvulsant therapy should be ...