Deletions of 2q14 that include the homeobox engrailed 1 (EN1) transcription factor are compatible with a normal phenotype

A novel transmitted 2 - 3Mb deletion of 2q14.1 - q14.2 was found in an affected boy from a consanguineous family with a possible diagnosis of PEHO syndrome ( OMIM 260565). BAC FISH showed that the deletion included a minimum of 20 genes including the homeobox engrailed 1 gene ( EN1). However, the same deletion was also found in his phenotypically normal father and brother ( family 1). The phenotype of the proband may, therefore, have been coincidental to the deletion, a result of a recessive condition within or outside the deleted segment or possibly due to variable dosage compensation of EN1 by the paralogous EN2 gene at 7q36. BAC FISH also showed that this deletion overlapped with a previously reported transmitted deletion of 2q13 - q14.1 that had no phenotypic consequences ( family 2). The deleted regions contained a total of 32 genes and comprise the final 5.25Mb of the ancestral chromosome 2B from which chromosome 2 was formed in man. These families provide further evidence that heterozygous deletions of regions of low gene density are compatible with a normal phenotype.