Editor—Interstitial deletions of the long arm of chromosome 16 share common clinical features including growth retardation, failure to thrive, microcephaly, high and prominent forehead, prominent metopic suture, large anterior fontanelle, hypertelorism, broad nasal bridge, low set and dysplastic ears, cleft palate, micrognathia, short neck, narrow thorax, broad first toes, mental retardation, muscular hypotonia, congenital heart defects, and gastrointestinal as well as renal anomalies.1 More than 26 patients with different interstitial long arm deletions of chromosome 16 have been reported.2-29 Recently, mutations in the transcription factor gene SALL1 on chromosome 16q12.130 were shown to result in Townes-Brocks syndrome, an autosomal dominantly inherited malformation syndrome characterised by malformations of the anus, hands, and ears as well as deafness.31 We describe a fetus with the 16q deletion syndrome and additional features, including unilateral radial aplasia, ulnar hypoplasia, preaxial hexadactyly, and segmentation defects of the vertebral column. Some of these features overlap with the malformations seen in Townes-Brocks syndrome. We therefore investigated the hypothesis that the SALL1 gene was included within the deletion.

The 31 year old, gravida 2, para 1 (her first child is a healthy boy) was referred at 24 weeks gestation because her fetus had cleft lip and palate detected by ultrasound screening. Biometry showed asymmetrical growth retardation with a thoraco-abdominal diameter of 43 mm (<5th centile) corresponding to 19 weeks' gestation, while the BPD (60 mm) and femur length (41 mm) were within normal limits. Careful examination by ultrasound showed multiple fetal abnormalities. Dilatation of the lateral ventricles, a dilated third ventricle, and a cavum septum pellucidum were noted. Aplasia of the right radius was suspected. The left kidney was absent. The right kidney was supplied by two arteries. The heart showed tetralogy of Fallot with absent pulmonary valve, agenesis of the ductus arteriosus, …