AbstractObjectivesTo present the clinical, cytogenetic, and molecular cytogenetic findings of prenatally diagnosed interstitial deletion 10q25.2‐q26.1. The majority of distal 10q deletions are pure terminal deletions with breakpoints in 10q25 and 10q26. Only four patients have been described so far with interstitial deletions involving bands 10q25.2‐q26.1.MethodsPostmortem physical examination and autopsy of the foetus after medically terminated pregnancy. GTG‐banding, reverse painting, and FISH analysis with BAC clones on amniocyte metaphases were performed to determine the extent of the deletion.ResultsAt 20 weeks the eutrophic female foetus showed pronounced microretrogeny and hypertelorism, clubfeet as well as minor internal anomalies like pancreas anulare, atypically lobed liver, and missing choleocystis. Cardiac anomalies were not observed and the genitalia were of a normal female. The deletion encompasses 6‐Mb and is associated with hemizygosity for 30 genes, including the genes for beta‐tectorin, the beta‐1 adrenergic receptor, and the alpha‐2A adrenergic receptor.ConclusionAn interstitial deletion del(10)(q25.2q25.3 ∼ 26.11) was confirmed by FISH with mapped BAC clones. Clinical and molecular cytogenetic analyses of further interstitial 10q deletions are necessary to assess whether the phenotypic manifestations differ between deletions that are interstitial compared to those that include also the terminal region of chromosome 10. Copyright © 2005 John Wiley & Sons, Ltd.