Novel methylenetetrahydrofolate reductase (MTHFR) mutation presenting with neonatal encephalopathy, hair loss and marfanoid features.

We present a case of a male term neonate with lethargy, hypotonia, hypoventilation and severe encephalopathy. The infant had a history of two siblings who died in the neonatal period from unclear causes. The infant exhibited skin and hair abnormalities, including desquamation of the extremities, angular stomatitis, cheilitis, neonatal acne and thin, sparse hair. Additionally, the infant had a tall stature; long, slender fingers and toes; and facial dysmorphism characterised by a long, narrow face with increased interpalpebral distance. The condition deteriorated rapidly, and unfortunately, death occurred before a definitive diagnosis could be established. Tandem mass spectrometry suggested low methionine and clinical exome sequencing identified a nonsense mutation in the MTHFR gene.