Fig. 3.

MRI of patient #1 at various ages. a. T2-weighted sequence, axial image at age 13 days, shows “very white” white matter and a rather rounded cortex, consistent with a diffuse encephalopathy. Intraventricular haemorrhage (arrowhead) is a change frequently encountered in the vulnerable neonatal brain, especially in premature babies. Absence of hypointense posterior limb of internal capsule (PLIC) (arrow) was an early indication of leukoencephalopathy. b. T2-weighted sequence, axial image at age 3.5 months and with reduced head circumference, shows increased extra-axial cerebrospinal fluid space frontally (*) with dilated ventricular system, consistent with reduced brain volume. Note small hyperintense thalami and lack of myelination with persisting absence of PLIC (arrow). C. Diffusion sequence, axial plane at age 3.5 months. There is restricted diffusion at areas where myelinated white matter should exist. This is evident as hyperintensity at the internal capsules (*) and at periventricular white matter around the frontal and occipital horns (arrowheads). D. Spectroscopy at 145 TE shows a glycine peak at 3.35 ppm (arrow). The clinical, imaging and biochemical diagnosis of glycine encephalopathy was confirmed by the identification of the p.Arg222Cys (c.664C>T) and p.Ser77Leu (c.230C>T) AMT gene variants in compound heterozygosity.