Difficult Diagnosis in a Patient with Phenylketonuria (PKU) and Metachromatic Leukodystrophy (MLD)

Abstract

Abstract Introduction Since phenylalanine level was included in the national newborn screening program in Egypt, patients with phenylketonuria (PKU) were early diagnosed and management and have better outcome with nearly normal motor and mental development. Neuro-regression or poor cognition is never recognized in compliant patients. Case presentation Herein we present an Egyptian child who was diagnosed by neonatal screening as PKU who was compliant on dietary treatment and normal development. After the age of 18 months, he started to loose previously acquired developmental milestones. Because of his average phenylalanine levels all through, a second neurodegenerative disease was suspected. Several investigations were done and the diagnosis of metachromatic leukodystrophy was suspected and was later confirmed by molecular testing showing homozygous frame shift mutation in ARSA gene c.583del, p. (Trp 195Glyfs*5) in addition to homozygous Missense mutation in PAH gene c.842C>T, p. (Pro281 Leu). Conclusion The presence of two genetic diseases in the same family should be suspected in consanguineous communities like ours especially if the clinical data of the primary disease does not fit.