Expanding spectrum of Rett syndrome-like and Angelman syndrome-like conditions

"Atypical" Rett or Angelman syndrome mimics	Features
MBD5/2q31.1 microdeletion	Minimal speech, seizures, microcephaly, behavioral disorders, short stature, coarse facies
FOXG1/chromosome 14 microdeletion	Congenital microcephaly, epilepsy, Rett-like phenotype, synophrys, dyskinesia
SLC9A6 (Christianson syndrome)	Epilepsy, ataxia, acquired microcephaly, lack of speech, slender body habitus
TCF4 Pitt-Hopkins syndrome/18q21.1 microdeletion	Wide mouth, fleshy lips, intermittent overbreathing
Atypical adenylosuccinate lyase deficiency	Hyperactivity, severe speech deficits, seizures, happy disposition, stereotypies

References:

Williams SR, Mullegama SV, Rosenfeld JA, et al. Haploinsufficiency of MBD5 associated with a syndrome involving microcephaly, intellectual disabilities, severe speech impairment, and seizures. Eur J Hum Genet 2010; 18:436.
Jacob FD, Ramaswamy V, Andersen J, Bolduc FV. Atypical Rett syndrome with selective FOXG1 deletion detected by comparative genomic hybridization: case report and review of literature. Eur J Hum Genet 2009; 17:1577.
Bahi-Buisson N, Nectoux J, Girard B, et al. Revisiting the phenotype associated with FOXG1 mutations: two novel cases of congenital Rett variant. Neurogenetics 2010; 11:241.
Gilfillan GD, Selmer KK, Roxrud I, et al. SLC9A6 mutations cause X-linked mental retardation, microcephaly, epilepsy, and ataxia, a phenotype mimicking Angelman syndrome. Am J Hum Genet 2008; 82:1003.
Zweier C, Peippo MM, Hoyer J, et al. Haploinsufficiency of TCF4 causes syndromal mental retardation with intermittent hyperventilation (Pitt-Hopkins syndrome). Am J Hum Genet 2007; 80:994.
Gitiaux C, Ceballos-Picot I, Marie S, et al. Misleading behavioural phenotype with adenylosuccinate lyase deficiency. Eur J Hum Genet 2009; 17:133.

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