Acrofacial Dysostosis Miller Type

At a glance

Postaxial limb deficiency with shortened limbs, absence of the fifth digit of hands and feet, and significant facial anomalies.

Synonyms

Postaxial Acrofacial Dysostosis; Miller Acrofacial Dysostosis; POADS (Postaxial Acrofacial Dysostosis Syndrome); Genée-Wiedemann Syndrome.

Incidence

Approximately 40 cases have been described.

Genetic inheritance

Miller acrofacial dysostosis is inherited as an autosomal recessive trait and is apparent at birth. The mutations affect the dihydroorotate dehydrogenase (DHODH) gene located on chromosome 16q22.2. It is unknown, how the mutations of DHODH lead to Miler Syndrome. The primary function of DHODH is to catalyze the conversion from dihydroorotate to orotic acid, which is an intermediate in the pyrimidine biosynthesis pathway. Orotic acid is then converted to uridine monophosphate.

Diagnosis

Based on the clinical findings, family history and genetic studies.

Clinical aspects

Intelligence in these patients is typically normal. They present with shortened forearms and lower legs secondary to postaxial limb deficiency (hypoplasia or aplasia of the posterior elements of the limbs) and bi- or unilateral absence of the fifth digit on hands (sometimes including the fifth metacarpal) and feet (in some cases, third and fourth toe are affected). Sporadically, radioulnar synostosis and syndactyly are present. Common facial anomalies consist of downslanting palpebral fissures, eyelid colobomas, lower lid ectropion, small, protruding and cup-shaped ears, malar hypoplasia, severe micrognathia, cleft palate (present in almost all reported patients), cleft lip (present in 20% of cases), and choanal stenosis/atresia. Other, more infrequent findings include cardiac anomalies (eg, atrial and ventricular septal defects, patent ductus arteriosus), abnormal sternum with segmentation failure and pectus anomaly, supernumerary vertebrae, ribs and nipples, urinary tract and genital anomalies (mainly cryptorchidism), single umbilical artery, and low-arch dermatoglyphics.

Precautions before anesthesia

Because of choanal stenosis or atresia, patency of the nasal passage should be examined before induction of anesthesia if nasal intubation is planned. Look for symptoms of obstructive sleep apnea. Assess for cardiac defects and obtain an echocardiography as required.

Anesthetic considerations

If difficult airway management is a risk, then it is recommended to maintain spontaneous ventilation until the airway has been secured. Alternative airway management options should be immediately available (eg, supraglottic airway device, fiberoptic bronchoscope) and adherence to an established difficult airway algorithm is advised. A surgeon familiar with surgical airway management and the necessary equipment should easily be available in the operating room. Awake fiberoptic intubation should be considered. In one case report, face-mask ventilation was awkward requiring a two-hand technique and an oral airway to overcome complete airway obstruction. Direct laryngoscopy revealed a Cormack-Lehane Grade II (only arytenoids visible) and intubation was achieved blindly with the help of a gum-elastic bougie. Cardiac anomalies may ...