Objective: our study aimed at retrospectively assessing the abnormal prenatal ultrasound findings of chromosome 4p deletion syndrome. Methods: 21 cases with abnormal sonographic signs revealed 4p deletion by Chromosome Microarray (CMA) in this retrospective analysis. Clinical information and molecular basis of this cohort were compared with those from other two groups in China, the critical region related to special ultrasound findings was mapped with the smallest regions of overlap. Results: This is the largest prenatal series to evaluate the prenatal ultrasound features of 4p deletion syndrome detected by CMA. Firstly we refined the relationship between the genomic coordinates with IUGR in chromosome 4p terminal deletion syndrome. Additional chromosomal abnormalities was identified in 12 cases. Intrauterine embryonic arrest was diagnosed at first trimester for 9 cases. The most consistent ultrasound indicator was IUGR (95.5%), and the smallest region response for IUGR correspond to a 2.05Mb at 4p16.3-pter (chr4: 68,345-2,121,057, hg19). Increased Nuchal Translucency (NT) could be a risk factor for predicting WHS at first-trimester pregnancy with the rate of 16.6% from our data. A 3.6Mb microdeletion located at 4p16.3-pter (chr4: 68,345-3,753,422, hg19) might be the candidate region associated with increased NT. Conclusion: We identified IUGR as the most common feature in prenatal 4p terminal deletion and Wolf-Hirschhorn syndrome. The existence of additional CNVs may contribution to possible explanations for the clinical heterogeneity of this syndrome. Prenatal findings of IUGR, increased NT or early spontaneous abortion should warrant the diagnosis of 4p terminal deletion WHS.
