OHDO SYNDROME IN A BOY WITH TERMINAL DELETION OF 4q AND DUPLICATION OF 10q

Objectives: Ohdo syndrome (OS) (MIM 249620) is a rare multiple malformation syndrome of unknown aetiology characterized by blepharophimosis, ptosis, dental hypoplasia, hearing impairment and mental retardation. We report on a child with presumed diagnosis of OS and an unbalanced submicroscopic chromosomal rearrangement involving the long arms of chromosome 4 and 10. Methods: Case report.

Results: 15 months old boy, first child of unrelated parents with severe bilateral blepharophimosis and ptosis, bilateral cataract, depressed nasal bridge, anteverted nostrils, macrostomia, macroglossia, bowed upper lip, malformed low-set ears, left broad thumb, severe muscular hypotonia, growth retardation, microcephaly, severe developmental delay (DQ 50). Dentition was delayed; hearing was clinically preserved. Cytogenetic analysis: normal conventional karyotype on peripheral blood lymphocytes. Fluorescence in-situ hybridization (FISH) with specific subtelomeric probes was performed, revealing a terminal deletion of 4q and a duplication of 10q [46,XY, del (4q), dup (10q)]. Karyotyping of the parents showed a balanced reciprocal translocation between chromosome 4 and 10 in the father [46,XY, t (4q; 10q)]. Conclusion: 1) The clinical findings of our patient correspond to patients with OS or Ohdo-like syndrome or to patients carrying terminal duplications of 10q. Since deletions of 4q result in different phenotypes, it is highly probable that the major features observed in our patient are caused by the duplication of 10q. 2) We propose that FISH studies should be done in patients with a phenotype of OS or Ohdo-like syndrome for diagnostic purposes and mainly genetic counselling. 3) As the phenotype of patients with terminal duplications of 10q is similar to patients with OS or Ohdo-like syndrome, we speculate that similar chromosomal rearrangements as in our patient might be responsible for the OS.