Classical Phenylketonuria and Antley-Bixler Syndrome Co-exist in a Patient

Phenylketonuria (PKU) is an uncommon metabolic disease in the Arab world. Antley-Bixler Syndrome (ABS) is a rare genetic disorder described by Antley and Bixler in 1975.Our patient MH was born at 38 weeks by spontaneous vaginal delivery. Parents are not consanguineous. The patient developed neonatal apnea and required mechanical ventilation. Routine newborn metabolic screening revealed phenylalanine level of 1285 m mol/L (38-137) consistent with classical PKU. MH responded well to phenylalanine free diet and the level remains within an acceptable range. DNA study confirmed that MH carries a homozygous known mutation, R261 in exon 7 which is leading to a codon stop. Clinical examination revealed microcephaly, craniocynstosis, brachycephaly, bossing, mid facial hypoplasia, depressed nasal bridge, bilateral proptosis and low set rotated ears. These dysmorphic features are consistent with Antley-Bixler Syndrome. Chromosomes and MRI brain were normal. MH developed recurrent apnea, epilepsy, eustachian tube dysfunction and hypotonia. Intellectually he was normal.It is extremely unusual to have two rare genetic disorders present in one patient. Here we report the co-existence of two rare genetic disorders in one Saudi boy.