An unusual phenotype of X-linked developmental delay and extreme behavioral difficulties associated with a mutation in the EBP gene.
We report on a family in which four males over three generations are affected with X-linked recessive developmental delay, learning difficulties, severe behavioral difficulties and mild dysmorphic features. Plasma sterol analysis in three of the four affected males demonstrated increased concentrations of 8-dehydrocholesterol (8-DHC) and cholest-8(9)-enol. All four affected males had a novel hemizygous missense mutation, p.W47R (c.139T>C), in EBP. Functional studies showed raised levels of cholest-8(9)-enol in patient's cultured fibroblast cells, which were suppressed when the cells were incubated with simvastatin. EBP encodes 3β-hydroxysteroid-delta8, delta7-isomerase, a key enzyme involved in the cholesterol biosynthesis pathway. Mutations in EBP have previously been associated with Conradi-Hunermann-Happle syndrome (CHH), an X-linked dominant disorder characterized by skeletal dysplasia, skin, and ocular abnormalities, which is usually lethal in males. Four previous reports describe X-linked recessive multiple anomaly syndromes associated with non-mosaic EBP mutations in males, two at the same amino acid position, p.W47C. This phenotype has previously been described as "MEND" syndrome (male EBP disorder with neurological defects). The family reported herein represent either a novel phenotype, or an expansion of the MEND phenotype, characterized by extreme behavioral difficulties and a scarcity of structural anomalies. Simvastatin therapy is being evaluated in two males from this family.
Yorkshire Regional Genetics Service, Chapel Allerton Hospital, Leeds, UK.
Verity L
VL
Hartill
Carolyn
C
Tysoe
Nigel
N
Manning
Angus
A
Dobbie
Saikat
S
Santra
John
J
Walter
Richard
R
Caswell
Janet
J
Koster
Hans
H
Waterham
Emma
E
Hobson
D000328:Adult; D002648:Child; D002775:Cholestadienols / Q000097:blood; D002658:Developmental Disabilities / Q000097:blood / Q000235:genetics*; D050172:Genes, X-Linked / Q000235:genetics*; D040181:Genetic Diseases, X-Linked / Q000097:blood / Q000235:genetics*; D006801:Humans; D007223:Infant; D008297:Male; D001523:Mental Disorders / Q000097:blood / Q000235:genetics*; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D013251:Steroid Isomerases / Q000235:genetics*; D055815:Young Adult
D002775:Cholestadienols; C026359:cholesta-5,8-dien-3 beta-ol; D013251:Steroid Isomerases; C090445:EBP protein, human
Conradi-Hunermann syndrome; Conradi-Hunermann-Happle syndrome; X-linked recessive inheritance; chondrodysplasia punctata, X-linked dominant; emopamil binding protein, human; sterol biosynthesis