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Short stature, round face, and hypertelorism. Cervical
hypermotility and odontoid subluxation.
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Aarskog-Scott Syndrome; Faciogenital Dysplasia;
Faciodigitogenital Syndrome.
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First described in 1970 by Dagfinn Aarskog, a Norwegian
pediatric endocrinologist.
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Approximately 200 cases have been reported to date.
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Most likely X-linked recessive. Genetic
heterogeneity or autosomal dominant inheritance with strong sex influence is
possible.
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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.
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Clinical features are recognizable at birth. Radiologic
findings include cervical spine abnormalities with subluxation, facial
abnormalities, phalangeal defects, and delayed bone age.
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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.
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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.
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Potentially difficult airway management
in case of mandibular deformity. Excessive hyperextension must be avoided
because of risk for cervical luxation during ...