The expanding role of MBD genes in autism: identification of a MECP2 duplication and novel alterations in MBD5, MBD6, and SETDB1.
The methyl-CpG-binding domain (MBD) gene family was first linked to autism over a decade ago when Rett syndrome, which falls under the umbrella of autism spectrum disorders (ASDs), was revealed to be predominantly caused by MECP2 mutations. Since that time, MECP2 alterations have been recognized in idiopathic ASD patients by us and others. Individuals with deletions across the MBD5 gene also present with ASDs, impaired speech, intellectual difficulties, repetitive behaviors, and epilepsy. These findings suggest that further investigations of the MBD gene family may reveal additional associations related to autism. We now describe the first study evaluating individuals with ASD for rare variants in four autosomal MBD family members, MBD5, MBD6, SETDB1, and SETDB2, and expand our initial screening in the MECP2 gene. Each gene was sequenced over all coding exons and evaluated for copy number variations in 287 patients with ASD and an equal number of ethnically matched control individuals. We identified 186 alterations through sequencing, approximately half of which were novel (96 variants, 51.6%). We identified 17 ASD specific, nonsynonymous variants, four of which were concordant in multiplex families: MBD5 Tyr1269Cys, MBD6 Arg883Trp, MECP2 Thr240Ser, and SETDB1 Pro1067del. Furthermore, a complex duplication spanning of the MECP2 gene was identified in two brothers who presented with developmental delay and intellectual disability. From our studies, we provide the first examples of autistic patients carrying potentially detrimental alterations in MBD6 and SETDB1, thereby demonstrating that the MBD gene family potentially plays a significant role in rare and private genetic causes of autism.
John P. Hussman Institute for Human Genomics, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
Holly N
HN
Cukier
Joycelyn M
JM
Lee
Deqiong
D
Ma
Juan I
JI
Young
Vera
V
Mayo
Brittany L
BL
Butler
Sandhya S
SS
Ramsook
Joseph A
JA
Rantus
Alexander J
AJ
Abrams
Patrice L
PL
Whitehead
Harry H
HH
Wright
Ruth K
RK
Abramson
Jonathan L
JL
Haines
Michael L
ML
Cuccaro
Margaret A
MA
Pericak-Vance
John R
JR
Gilbert
D000293:Adolescent; D000328:Adult; D001321:Autistic Disorder / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D056915:DNA Copy Number Variations / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D020440:Gene Duplication / Q000235:genetics*; D020022:Genetic Predisposition to Disease / Q000235:genetics; D011495:Histone-Lysine N-Methyltransferase; D006801:Humans; D008297:Male; D051783:Methyl-CpG-Binding Protein 2 / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011496:Protein Methyltransferases / Q000235:genetics*; D055815:Young Adult
D004268:DNA-Binding Proteins; C550332:MBD5 protein, human; C553236:MBD6 protein, human; D051783:Methyl-CpG-Binding Protein 2; D011496:Protein Methyltransferases; D011495:Histone-Lysine N-Methyltransferase; C454062:SETDB1 protein, human