Table 3.

Neurodevelopmental Disorders of Interest in the Differential Diagnosis of Schaaf-Yang Syndrome (SYS)

Gene(s) / Genetic MechanismDiffDx DisorderMOIOccurrence of Feature in Persons w/DiffDx Disorder
ID/DDASDNeonatal hypotoniaInfantile feeding problemsDistal joint contractures
Deletions, maternal UPD, imprinting errors w/in PWCR 1 Prader-Willi syndrome See footnote 2.+++++++++++±
ERGIC1
LGI4
SCYL2
SYNE1
TOR1A 		Arthrogryposis multiplex congenita (See SYNE1 Deficiency & OMIM PS617468.)AR++−VariableVariable+++
SMN1 Spinal muscular atrophy type 1AR−−++++++−
Interstitial deletions on chromosome 16q22 3Chromosome 16q22 deletion syndrome (OMIM 614541)AD
(isolated cases)		++−+++++−
AGRN
ALG2
ALG14
CHAT
CHRNA1
CHRNB1
CHRND
CHRNE
COL13A1
COLQ
DOK7
DPAGT1
GFPT1
LRP4
MUSK
MYO9A
PREPL
RAPSN
SCN4A
SLC18A3
SLC5A7
SLC25A1
SNAP25
SYT2
VAMP1 		Congenital myasthenic syndromes 4AD
AR		+−++++++

+++ = core feature in this disorder; ++ = variable feature of this disorder; + = rare feature of this disorder; – = not typically associated with this disorder; AD = autosomal dominant; AR = autosomal recessive; ASD = autism spectrum disorder; DD = developmental delay; DiffDx = differential diagnosis; ID = intellectual disability; MOI = mode of inheritance; PWCR = Prader-Willi critical region; UPD = uniparental disomy

1.
2.

The risk to the sibs of an affected child of having PWS depends on the genetic mechanism that resulted in the absence of expression of the paternally contributed 15q11.2-q13 region.

3.

Infants may present with clenched or flexed fingers.

4.

See also Phenotypic Series: Congenital Myasthenic Syndrome for genes associated with this phenotype in OMIM.

From: Schaaf-Yang Syndrome

Cover of GeneReviews®
GeneReviews® [Internet].
Adam MP, Feldman J, Mirzaa GM, et al., editors.
Seattle (WA): University of Washington, Seattle; 1993-2024.
Copyright © 1993-2024, University of Washington, Seattle. GeneReviews is a registered trademark of the University of Washington, Seattle. All rights reserved.

GeneReviews® chapters are owned by the University of Washington. Permission is hereby granted to reproduce, distribute, and translate copies of content materials for noncommercial research purposes only, provided that (i) credit for source (http://www.genereviews.org/) and copyright (© 1993-2024 University of Washington) are included with each copy; (ii) a link to the original material is provided whenever the material is published elsewhere on the Web; and (iii) reproducers, distributors, and/or translators comply with the GeneReviews® Copyright Notice and Usage Disclaimer. No further modifications are allowed. For clarity, excerpts of GeneReviews chapters for use in lab reports and clinic notes are a permitted use.

For more information, see the GeneReviews® Copyright Notice and Usage Disclaimer.

For questions regarding permissions or whether a specified use is allowed, contact: ude.wu@tssamda.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.