Yunis-Varon Syndrome

A severe polymalformative syndrome characterized by facial dysmorphism, absent clavicle, and extremity abnormalities. Often lethal within few months because of the failure to thrive and severe cardiorespiratory dysfunction.

Cleidocranial Dysplasia with Micrognathia, Absent Thumbs, and Distal Aphalangia.

First described by E. Yunis and H. Varon in 1980.

Unknown (fewer than 20 case reports worldwide).

Autosomal recessive.

Unknown. A lysosomal storage disorder has been evocated.

Suggested by prenatal ultrasonography, as well as by specific clinical features, including growth retardation prior to and after birth. Defective growth of the bones of the skull along with complete or partial absence of the shoulder blades (cleidocranial dysplasia) associated with characteristic facial features (severe micrognathia) and abnormalities of the fingers and toes complete the diagnosis.

Patients have marked psychomotor delay, postnatal failure to thrive, severe feeding problems, and respiratory difficulties. Clinical signs can involve head and neck (macrocrania with diastasis of cranial sutures; calvarial dysostosis; sparse scalp hair; hypoplastic facial bones; bitemporal indentations; small eyes; proptosis; low-set, dysplastic ears; anteverted nostrils; narrow and high-arched palate; severe micrognathia; occasional glossoptosis [moderate]; retracted and poorly delineated lips with diminished nasolabial distance), skeleton (absent clavicles; absent sternal ossification; pelvic dysplasia with hip dislocation; hypoplasia of thumbs; middle and distal aphalangia of the other fingers; agenesis of the first metatarsals; hypoplastic proximal phalanges of the big toes; delayed bone maturation; occasional pathological fractures; and nail hypoplasia), CNS (arhinencephaly; absent corpus callosum; hypoplasia of the vermis; neuronal loss and vacuolation involving cerebral cortex; basal ganglia; cerebellar dentate nuclei and spinal anterior horns; hypertonia and hypotonia have also been reported), and heart (cardiomyopathy, tetralogy of Fallot). The majority of patients die in infancy as a result of severe failure to thrive and recurrent pneumonia.

A complete evaluation of the airway is indicated (clinical, radiographs). The cardiac function must be assessed for the potential association of congenital heart defects. An echocardiogram is most useful in this situation. Evaluate neurological function (clinical, CT, EEG). Blood examination must include a complete blood cell count because of frequent infections. Also, the hemoglobin, electrolytes, and glucose must be obtained. If the patient is on parenteral nutrition for failure to thrive, obtain albumin levels, liver enzymes, and bilirubin. Consider sedative premedication in older children with developmental delay.

There is no literature available about this condition. Because of the presence of facial anomalies suggesting the possibility of difficult airway management, it is recommended to maintain spontaneous ventilation until the airway has been secured and lung ventilation confirmed. The availability of a laryngeal mask airway and/or fiberoptic equipment is required. Particular attention should be given to the positioning of the patient intraoperatively (pathological fractures). Proper padding must be ensured to reduce pressure point complications. Venous access can be difficult because of extremity malformations. Central venous access using the subclavian route should be avoided because of the ...