1. ¹National Genetics Reference Laboratory (Wessex), Salisbury NHS Foundation Trust, Salisbury, Wiltshire, UK
2. ²Wessex Regional Genetics Laboratory, Salisbury NHS Foundation Trust, Salisbury, Wiltshire, UK
3. ³Human Genetics Division, Southampton University School of Medicine, Southampton General Hospital, Southampton, UK
4. ⁴Leicestershire Genetics Centre, Leicester Royal Infirmary, Leicester
5. ⁵Institute of Human Genetics, International Centre for Life, Central Parkway, Newcastle upon Tyne, UK
6. ⁶James Cook University Hospital, Marton Road, Middlesbrough, Cleveland, UK
7. ⁷Regional Cytogenetics Unit, St James Hospital, Beckett Street, Leeds, UK
8. ⁸Clinical Genetics, St James Hospital, Beckett Street, Leeds, UK

Correspondence: Dr JCK Barber, Wessex Regional Genetics Laboratory, Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ, UK. Tel: +44 (0)1722 429080; Fax: +44 (0)1722 338095; E-mail: john.barber@salisbury.nhs.uk

Received 3 July 2007; Revised 23 August 2007; Accepted 30 August 2007; Published online 17 October 2007.

Abstract

The 8p23.1 deletion syndrome is established but not an equivalent duplication syndrome. Here, we report five patients; a de novo prenatal case and two families in which 8p23.1 duplications have been directly transmitted from mothers to children. Dual-colour fluorescent in situ hybridisation, multiplex ligation-dependent probe amplification analysis and customised oligonucleotide array comparative genomic hybridisation (oaCGH) indicated an 3.75 Mb duplication of most of band 8p23.1 between the olfactory receptor/defensin repeats (ORDRs) in all cases. However, oaCGH revealed an additional duplication of 500 kb adjacent to the proximal ORDR in Family 1 and an additional deletion of 3.14 Mb within the Nablus Mask-Like Facial Syndrome region of 8q22.1 in Family 2. Copy number variation at introns 4–5 of the GATA4 gene was also identified. This 8p23.1 duplication syndrome is associated with a characteristic facial phenotype including a prominent forehead and arched eyebrows. Adrenal insufficiency, Tetralogy of Fallot, partial 2/3 syndactyly of the toes and cleft palate in some individuals may be explained by ascertainment bias, incomplete penetrance and/or the presence of the microdeletion in Family 2. The duplication is compatible with normal early childhood development but, although our adult cases live independent lives with varying degrees of support, learning difficulties have been experienced by some family members. We conclude that the 8p23.1 duplication syndrome is a genomic condition with an emerging but variable phenotype that may be under-diagnosed. Our results demonstrate that direct transmission does not distinguish genuine duplications from euchromatic variants and illustrate the power of array CGH to reveal unexpected additional imbalances in affected patients.