Aprosencephaly Syndrome

Clinical Features

Townes et al. (1988) described a sibship in which there were twins with anencephaly and a female infant with aprosencephaly, fused humerus and radius, and oligodactyly. Townes et al. (1988) suggested that the XK aprosencephaly syndrome may be an autosomal recessive disorder. The authors noted that Garcia and Duncan (1977) and Lurie et al. (1979, 1980) had described patients with a disorder similar to that of the female infant.

Martin and Carey (1982) reported another case.

Labrune et al. (1997) described 6 fetuses with normal chromosomes and severe craniofacial, limb, and visceral malformations observed during the second trimester of pregnancy. Two of these fetuses were monozygotic twins while a third one had a healthy dizygotic twin brother. One case of familial recurrence was observed. Autopsy and skeletal radiograph suggested several diagnoses, including XK aprosencephaly. The experience strengthened the possibility of autosomal recessive inheritance.

Renzetti et al. (2005) reported a girl with XK syndrome born to Libyan parents. She had a sloping forehead, microphthalmia, beaked nose, absent right thumb, and cutaneous syndactyly of toes 2 and 3. MRI and ophthalmic examinations showed microencephaly, pachygyria, and absent anterior chamber of the right eye. Her facial appearance was similar to that of her older brother who had died at age 18 months of respiratory failure. The familial component suggested autosomal recessive inheritance. An unrelated affected infant showed hypotelorism with craniofacial anomalies, abnormalities of the arms, and almost total aprosencephaly with focally displaced remnants of neural tissue.

Renzetti et al. (2005) reviewed the literature concerning XK syndrome and commented on the clinical variability and heterogeneity of the disorder. The authors concluded that it results from a developmental field defect.

Nomenclature

Lurie et al. (1979) coined the term 'aprosencephaly' and suggested the designation 'XK aprosencephaly syndrome,' with 'X' referring to the unknown surname of the patient described by Garcia and Duncan (1977) and 'K' to the surname of their patient.