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Clinical and molecular characteristics of 1qter microdeletion syndrome: delineating a critical region for corpus callosum agenesis/hypogenesis
  1. B W M van Bon1,
  2. D A Koolen1,
  3. R Borgatti2,
  4. A Magee3,
  5. S Garcia-Minaur4,
  6. L Rooms5,
  7. W Reardon6,
  8. M Zollino7,
  9. M C Bonaglia3,
  10. M De Gregori8,
  11. F Novara8,
  12. R Grasso2,
  13. R Ciccone8,
  14. H A van Duyvenvoorde9,
  15. A M Aalbers9,
  16. R Guerrini10,
  17. E Fazzi11,
  18. W M Nillesen1,
  19. S McCullough3,
  20. S G Kant9,
  21. C L Marcelis1,
  22. R Pfundt1,
  23. N de Leeuw1,
  24. D Smeets1,
  25. E A Sistermans1,
  26. J M Wit9,
  27. B C Hamel1,
  28. H G Brunner1,
  29. F Kooy5,
  30. O Zuffardi8,12,
  31. B B A de Vries1
  1. 1
    Department of Human Genetics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
  2. 2
    IRCCS Eugenio Medea La Nostra Famiglia, Bosisio Parini, Lecco, Italy
  3. 3
    Northern Ireland Regional Genetics Service, Belfast City Hospital Trust, Belfast, Northern Ireland
  4. 4
    South East of Scotland Clinical Genetic Service, Western General Hospital, Edinburgh, UK
  5. 5
    Department of Medical Genetics, University of Antwerp, Antwerp, Belgium
  6. 6
    National Centre for Medical Genetics, Our Lady’s Hospital for Sick Children, Crumlin, Dublin, Ireland
  7. 7
    Istituto di Genetica Medica, Universitè Cattolica Sacro Cuore, Rome, Italy
  8. 8
    Genetica Medica, Universitè di Pavia, Pavia, Italy
  9. 9
    Dept of Clinical Genetics, Dept of Pediatrics and Dept of Endocrinology and Metabolism, Leiden University Medical Center, Leiden, The Netherlands
  10. 10
    Azienda Ospedaliero-Universitaria A Meyer, Clinica di Neurologia Pediatrica, Firenze, Italy
  11. 11
    Department of Child Neurology and Psychiatry, IRCCS C Mondino Institute of Neurology, Pavia, Italy
  12. 12
    IRCCS Fondazione Policlinico San Matteo, Pavia, Italy
  1. Dr B B A de Vries, Department of Human Genetics 849, RUNMC, PO Box 9101 6500 HB Nijmegen, The Netherlands; b.devries{at}


Background: Patients with a microscopically visible deletion of the distal part of the long arm of chromosome 1 have a recognisable phenotype, including mental retardation, microcephaly, growth retardation, a distinct facial appearance and various midline defects including corpus callosum abnormalities, cardiac, gastro-oesophageal and urogenital defects, as well as various central nervous system anomalies. Patients with a submicroscopic, subtelomeric 1qter deletion have a similar phenotype, suggesting that the main phenotype of these patients is caused by haploinsufficiency of genes in this region.

Objective: To describe the clinical presentation of 13 new patients with a submicroscopic deletion of 1q43q44, of which nine were interstitial, and to report on the molecular characterisation of the deletion size.

Results and conclusions: The clinical presentation of these patients has clear similarities with previously reported cases with a terminal 1q deletion. Corpus callosum abnormalities were present in 10 of our patients. The AKT3 gene has been reported as an important candidate gene causing this abnormality. However, through detailed molecular analysis of the deletion sizes in our patient cohort, we were able to delineate the critical region for corpus callosum abnormalities to a 360 kb genomic segment which contains four possible candidate genes, but excluding the AKT3 gene.

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  • Competing interests: None declared.

  • Patient consent: Informed consent was obtained from the patients and their families for publication of this report, and for the publication of fig 1.