Aarskog Syndrome

Short stature, round face, and hypertelorism. Cervical hypermotility and odontoid subluxation.

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Aarskog-Scott Syndrome; Faciogenital Dysplasia; Faciodigitogenital Syndrome.

First described in 1970 by Dagfinn Aarskog, a Norwegian pediatric endocrinologist.

Approximately 200 cases have been reported to date.

Most likely X-linked recessive. Genetic heterogeneity or autosomal dominant inheritance with strong sex influence is possible.

Gene FGD1 (responsible for faciogenital dysplasia) encodes a guanine nucleotide exchange factor that specifically activates Cdc42, a member of the Rho family of guanosine triphosphatases (GTPases) involved in cellular signaling, migration, growth, and differentiation. Mutations to the FGD1 gene result in a human developmental disorder affecting specific skeletal structures, including elements of the face, cervical vertebrae, and distal extremities.

Clinical features are recognizable at birth. Radiologic findings include cervical spine abnormalities with subluxation, facial abnormalities, phalangeal defects, and delayed bone age.

Patients present with anomalies of the face, genitalia, and limbs. Growth retardation usually becomes evident at age 2 to 4 years. Facial features may include a round face with hypertelorism, ophthalmoplegia, large cornea, hyperopic astigmatism, antimongoloid obliquity of the palpebral fissures, strabismus, and ptosis. The nose is short and stubby with anteverted nostrils. The philtrum is long with broad upper lip. Cleft lip/palate, a linear dimple below the lower lip, and enamel dysplasia are common. The midface is flattened secondary to maxillary hypoplasia and deformity of the anterior mandible. The ears are low-set, cup shaped, and floppy. Limb anomalies consist of short thumbs, digital contractures, syndactyly, clinodactyly, brachydactyly, camptodactyly, and simian creases. Abnormal genital findings include cryptorchidism, scrotal folds encircling the penis ventrally (shawl scrotum), and inguinal hernia. Associated heart defects have been described (e.g., pulmonary stenosis, ventricular septal defect). Mild developmental delay seems to be frequent. Other features are ligamentous laxity of the hands, knees, and feet, pectus excavatum, liver cirrhosis with portal hypertension, imperforated anus, macrocytic anemia, hemochromatosis, and broad flat feet with lymphedema.

Evaluate for neck hypermobility and subluxation secondary to ligamentous laxity and malformations of cervical vertebrae (odontoid). Look for associated neurologic symptoms. Cervical spine radiographs may be helpful. Assess the airway for difficult tracheal intubation. Exclude associated heart defects (ECG, echocardiography). Ask for a chest radiograph and pulmonary function tests in presence of pectus excavatum. Blood workup should include a complete blood count to rule out anemia or thrombocytopenia (secondary to hypersplenism in the presence of liver cirrhosis), a coagulation status, and liver function tests in liver cirrhosis patients.

Potentially difficult airway management in case of mandibular deformity. Excessive hyperextension must be avoided because of risk for cervical luxation during tracheal intubation. ...