Haploinsufficiency of a spliceosomal GTPase encoded by EFTUD2 causes mandibulofacial dysostosis with microcephaly.
Mandibulofacial dysostosis with microcephaly (MFDM) is a rare sporadic syndrome comprising craniofacial malformations, microcephaly, developmental delay, and a recognizable dysmorphic appearance. Major sequelae, including choanal atresia, sensorineural hearing loss, and cleft palate, each occur in a significant proportion of affected individuals. We present detailed clinical findings in 12 unrelated individuals with MFDM; these 12 individuals compose the largest reported cohort to date. To define the etiology of MFDM, we employed whole-exome sequencing of four unrelated affected individuals and identified heterozygous mutations or deletions of EFTUD2 in all four. Validation studies of eight additional individuals with MFDM demonstrated causative EFTUD2 mutations in all affected individuals tested. A range of EFTUD2-mutation types, including null alleles and frameshifts, is seen in MFDM, consistent with haploinsufficiency; segregation is de novo in all cases assessed to date. U5-116kD, the protein encoded by EFTUD2, is a highly conserved spliceosomal GTPase with a central regulatory role in catalytic splicing and post-splicing-complex disassembly. MFDM is the first multiple-malformation syndrome attributed to a defect of the major spliceosome. Our findings significantly extend the range of reported spliceosomal phenotypes in humans and pave the way for further investigation in related conditions such as Treacher Collins syndrome.
Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ontario, Canada.
Matthew A
MA
Lines
Lijia
L
Huang
Jeremy
J
Schwartzentruber
Stuart L
SL
Douglas
Danielle C
DC
Lynch
Chandree
C
Beaulieu
Maria Leine
ML
Guion-Almeida
Roseli Maria
RM
Zechi-Ceide
Blanca
B
Gener
Gabriele
G
Gillessen-Kaesbach
Caroline
C
Nava
Geneviève
G
Baujat
Denise
D
Horn
Usha
U
Kini
Almuth
A
Caliebe
Yasemin
Y
Alanay
Gulen Eda
GE
Utine
Dorit
D
Lev
Jürgen
J
Kohlhase
Arthur W
AW
Grix
Dietmar R
DR
Lohmann
Ute
U
Hehr
Detlef
D
Böhm
Jacek
J
Majewski
Dennis E
DE
Bulman
Dagmar
D
Wieczorek
Kym M
KM
Boycott
D000015:Abnormalities, Multiple / Q000235:genetics; D000483:Alleles; D000595:Amino Acid Sequence; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D059472:Exome; D005260:Female; D020558:GTP Phosphohydrolases / Q000235:genetics*; D057895:Haploinsufficiency / Q000235:genetics*; D006801:Humans; D007223:Infant; D008297:Male; D008342:Mandibulofacial Dysostosis / Q000235:genetics*; D008831:Microcephaly / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics; D017415:Ribonucleoprotein, U5 Small Nuclear / Q000235:genetics*; D017381:Spliceosomes / Q000235:genetics
D017415:Ribonucleoprotein, U5 Small Nuclear; C506012:TXNL4A protein, human; D020558:GTP Phosphohydrolases