The 2q23.1 microdeletion syndrome: clinical and behavioural phenotype.
Six submicroscopic deletions comprising chromosome band 2q23.1 in patients with severe mental retardation (MR), short stature, microcephaly and epilepsy have been reported, suggesting that haploinsufficiency of one or more genes in the 2q23.1 region might be responsible for the common phenotypic features in these patients. In this study, we report the molecular and clinical characterisation of nine new 2q23.1 deletion patients and a clinical update on two previously reported patients. All patients were mentally retarded with pronounced speech delay and additional abnormalities including short stature, seizures, microcephaly and coarse facies. The majority of cases presented with stereotypic repetitive behaviour, a disturbed sleep pattern and a broad-based gait. These features led to the initial clinical impression of Angelman, Rett or Smith-Magenis syndromes in several patients. The overlapping 2q23.1 deletion region in all 15 patients comprises only one gene, namely, MBD5. Interestingly, MBD5 is a member of the methyl CpG-binding domain protein family, which also comprises MECP2, mutated in Rett's syndrome. Another gene in the 2q23.1 region, EPC2, was deleted in 12 patients who had a broader phenotype than those with a deletion of MBD5 only. EPC2 is a member of the polycomb protein family, involved in heterochromatin formation and might be involved in causing MR. Patients with a 2q23.1 microdeletion present with a variable phenotype and the diagnosis should be considered in mentally retarded children with coarse facies, seizures, disturbed sleeping patterns and additional specific behavioural problems.
van Bon
Bregje W M
BW
Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Koolen
David A
DA
Brueton
Louise
L
McMullan
Dominic
D
Lichtenbelt
Klaske D
KD
Adès
Lesley C
LC
Peters
Gregory
G
Gibson
Kate
K
Moloney
Susan
S
Novara
Francesca
F
Pramparo
Tiziano
T
Dalla Bernardina
Bernardo
B
Zoccante
Leonardo
L
Balottin
Umberto
U
Piazza
Fausta
F
Pecile
Vanna
V
Gasparini
Paolo
P
Guerci
Veronica
V
Kets
Marleen
M
Pfundt
Rolph
R
de Brouwer
Arjan P
AP
Veltman
Joris A
JA
de Leeuw
Nicole
N
Wilson
Meredith
M
Antony
Jayne
J
Reitano
Santina
S
Luciano
Daniela
D
Fichera
Marco
M
Romano
Corrado
C
Brunner
Han G
HG
Zuffardi
Orsetta
O
de Vries
Bert B A
BB
D017204:Angelman Syndrome / Q000235:genetics; D002585:Cesarean Section; D002648:Child; D002874:Chromosome Mapping; D002889:Chromosomes, Human, Pair 2 / Q000235:genetics*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000235:genetics*; D007363:Intensive Care Units, Neonatal; D007859:Learning Disabilities / Q000235:genetics; D008297:Male; D010641:Phenotype; D015518:Rett Syndrome / Q000235:genetics; D017384:Sequence Deletion