Fig. 2

MR images in different PCH subtypes. a-b. Coronal (a) and midsagittal (b) image of severely affected PCH1B patient (age 3 weeks, homozygous for the p. G31A mutation in EXOSC3), showing severe hypoplasia of cerebellar hemisphere with relative sparing of the vermis (indicated by arrowhead). The ventral pons is reduced in size but not completely flattened (indicated by arrow). c-d. Coronal (c) and midsagittal (d) image of PCH1B patient (age 2,5 months) with milder EXOSC3 mutations(the patient is homozygous for the p.D132A mutation). Cerebellar hypoplasia is very mild, with bilateral hyperintensities in the hili of the dentate nucleus. Size and shape of the ventral pons are normal. e-f. Coronal (e) and midsagittal (f) image of PCH2A patient (age 7 days, homozygous for the TSEN54, p.A307S mutation) with severe flattening of cerebellar hemispheres with relative sparing of the vermis (indicated by arrowhead) resulting in the ‘dragonfly’ configuration typical of PCH2A. This pattern is also seen in some PCH1 patients, as shown in 1A. The ventral pons is reduced in size but not completely flattened. g-h. Coronal (g) and midsagittal (h) image of PCH4 patient (age 6 weeks, compound heterozygous for the p. A307S mutation and a frameshift mutation in the TSEN54 gene). Note severe flattening of pons and severe hypoplasia of the cerebellum without sparing of the vermis and profound supratentorial atrophy (indicated by asterisks). i-j. Coronal (i) and midsagittal (j) image of a PCH6 patient (age 6 months, compound heterozygous for mutations in the RARS2 gene) with strikingly rapid progression of supratentorial atrophy (indicated by asterisks) and relatively slight atrophy of cerebellar hemispheres with normal pons and brainstem. k-l. Coronal (k) and midsagittal (l) image of a PCH7 patient (age 8 months, with biallelic mutations in the TOE1 gene), showing severe pontocerebellar hypoplasia, equally affecting hemispheres and vermis. Note very thin corpus callosum and profound ventriculomegaly (indicated by asterisks and ^, respectively). m-n. Coronal and midsagittal image of a PCH9 patient (age 2 years, homozygous for a mutation in the AMPD2 gene), showing characteristic ‘figure 8’ shaped brainstem and corpus callosum agenesis (indicated by a circle and arrowhead, respectively).o-p. Coronal and midsagittal image of a control