Table 3.

TSEN54 gene‐related pontocerebellar hypoplasia. Adapted and extended from Namavar et. al (Namavar et al., 2011)

PCH subtype	Gene	MIM	Clinical features	Lethality	Pathological features	Ref.
PCH2	TSEN54, TSEN2, TSEN34	277470, 612389, 612390	Clonus and impaired swallowing during neonatal period. In Infancy and later: chorea, variable spastic paresis; progressive microcephaly. variable neocortical atrophy, and pontocerebellar hypoplasia are evident in MRI.	In Infancy and childhood.	Cerebellar hypoplasia. Segmental degeneration of cortex. Fragmentation of cerebellar dentate nucleus. Neuron loss and decreased folding in Olivary nucleus. progressive loss of ventral nuclei and transverse fibers in pons, and progressive atrophy in Cerebral cortex.	Barth et al. (1995), Valayannopoulos et al. (2011)
PCH4	TSEN54	225753	Polyhydramnios, hypertonia, severe clonus, and/or contractures and primary hypoventilation are evident in neonatal period. Delayed neocortical maturation, pontocerebellar hypoplasia; microcephaly on autopsy are discernable from MRI.	Early postnatal death from apnea	Cerebellar hypoplasia: hemispheres ≫vermis, areas of stunted or absent folial development. Cerebellar dentate nucleus presents as tiny remnants. Olivary nucleus: absent folding and gliosis. Pons: loss of ventral nuclei and transverse fibers.	Budde et al. (2008), Chaves‐Vischer et al. (2000)
PCH5	TSEN54	611523	Seizures in Prenatal/neonatal period and clonus during neonatal period. Persistent clonus, microcephaly and pontocerebellar hypoplasia on autopsy during the following months.	Early postnatal death from apnea	Cerebellar hypoplasia: cortical involvement as in PCH4, but vermal cortex more extensively affected than hemispheric cortex; subtotal loss of cerebellar dentate nucleus. Olivary nucleus: absent folding. Pons: loss of ventral nuclei and transverse fibers.	Patel, Becker, Toi, Armstrong, and Chitayat (2006)