A genotype-first approach for the molecular and clinical characterization of uncommon de novo microdeletion of 20q13.33.
BACKGROUND
Subtelomeric deletions of the long arm of chromosome 20 are rare, with only 11 described in the literature. Clinical features of individuals with these microdeletions include severe limb malformations, skeletal abnormalities, growth retardation, developmental and speech delay, mental retardation, seizures and mild, non-specific dysmorphic features.


RESULTS
We characterized microdeletions at 20q13.33 in six individuals referred for genetic evaluation of developmental delay, mental retardation, and/or congenital anomalies. A comparison to previously reported cases of 20q13.33 microdeletion shows phenotypic overlap, with clinical features that include mental retardation, developmental delay, speech and language deficits, seizures, and behavior problems such as autistic spectrum disorder. There does not appear to be a clinically recognizable constellation of dysmorphic features among individuals with subtelomeric 20q microdeletions.


CONCLUSIONS
Based on genotype-phenotype correlation among individuals in this and previous studies, we discuss several possible candidate genes for specific clinical features, including ARFGAP1, CHRNA4 and KCNQ2 and neurodevelopmental deficits. Deletion of this region may play an important role in cognitive development.
Traylor
Ryan N
RN
Signature Genomic Laboratories, Spokane, Washington, United States of America.
Bruno
Damien L
DL
Burgess
Trent
T
Wildin
Robert
R
Spencer
Anne
A
Ganesamoorthy
Devika
D
Amor
David J
DJ
Hunter
Matthew
M
Caplan
Michael
M
Rosenfeld
Jill A
JA
Theisen
Aaron
A
Torchia
Beth S
BS
Shaffer
Lisa G
LG
Ballif
Blake C
BC
Slater
Howard R
HR
D001526:Behavioral Symptoms / Q000235:genetics / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D002872:Chromosome Deletion; D002890:Chromosomes, Human, Pair 20 / Q000235:genetics*; D002658:Developmental Disabilities / Q000235:genetics / Q000503:physiopathology; D005260:Female; D005838:Genotype; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics / Q000503:physiopathology; D007806:Language Disorders / Q000235:genetics / Q000503:physiopathology; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D012640:Seizures / Q000235:genetics / Q000503:physiopathology; D013064:Speech Disorders / Q000235:genetics / Q000503:physiopathology
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