Beaulieu-Boycott-Innes syndrome: an intellectual disability syndrome with characteristic facies.
We report a female child from an Irish Traveller family presenting with severe intellectual disability, dysmorphic features, renal anomalies, dental caries and cyclical vomiting. Current health issues include global developmental delay, mild concentric left ventricular hypertrophy, dental malocclusion and caries and a single duplex left kidney. The proband and her mother also have multiple epiphyseal dysplasia. Whole-exome sequencing was performed to identify the underlying genetic cause. DNA from the proband was enriched with the Agilent Sure Select v5 Exon array and sequenced on an Illumina HiSeq. Rare homozygous variants were prioritized. Whole-exome sequencing identified three linked homozygous missense variants in THOC6 (c.298T>A, p.Trp100Arg; c.700G>C, p.Val234Leu; c.824G>A, p.Gly275Asp) as the likely cause of this child's intellectual disability syndrome, resulting in a molecular diagnosis of Beaulieu-Boycott-Innes syndrome (BBIS). This is the first report of BBIS in Europe. BBIS has been reported previously in two Hutterite families and one Saudi family. A review of all patients to date shows a relatively homogenous phenotype. Core clinical features include low birth weight with subsequent growth failure, short stature, intellectual disability with language delay, characteristic facies, renal anomalies and dental malocclusion with caries. Some patients also have cardiac defects. All patients show characteristic dysmorphic facial features including a tall forehead with high anterior hairline and deep-set eyes with upslanting palpebral fissures. The coexistence of intellectual disability together with these characteristic facies should provide a diagnostic clue for BBIS during patient evaluation.
aDepartment of Clinical Genetics bNational Centre for Inherited Metabolic Disorders, Temple Street Children's University Hospital cUCD Academic Centre on Rare Diseases, School of Medicine and Medical Sciences, University College Dublin dDepartment of Clinical Genetics, Our Lady's Children's Hospital, Dublin eNorthern Ireland Regional Genetics Service, Belfast City Hospital, Belfast, UK.
Jillian
J
Casey
Allan
A
Jenkinson
Alex
A
Magee
Sean
S
Ennis
Ahmad
A
Monavari
Andrew
A
Green
Sally A
SA
Lynch
Ellen
E
Crushell
Joanne
J
Hughes
D000483:Alleles; D002648:Child; D059472:Exome; D019066:Facies; D005260:Female; D005838:Genotype; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis* / Q000235:genetics*; D010375:Pedigree; D010641:Phenotype; D013577:Syndrome