Detailed postmortem findings from 11 cases of probable Fraser (cryptophthalmos-syndactyly) syndrome are reported. Eight cases presented as neonatal deaths, one as a stillbirth, and there were 2 midtrimester fetuses. All of the cases had ocular, otic, digital, laryngeal, and renal abnormalities. Details of the pregnancies and sibship data are also reported. The possibility of prenatal diagnosis for this syndrome is discussed.

The X‐linked FG syndrome is characterised by mental retardation, congenital hypotonia and constipation (which may both be severe), structural anal anomalies and relative macrocephaly in some, and an unusual and characteristic facial appearance. We describe 7 males from 4 families. One had anal stenosis. Two of the mothers and one sister show probable carrier manifestations. The features of the FG syndrome are individually non‐specific. We emphasize that the characteristic combination of features is needed to avoid overdiagnosis.

The gene coding for sucrase-isomaltase (SI) has recently been mapped to chromosome 3 using a cDNA probe to analyse DNA from somatic cell hybrids (Green et al. 1987). We have now used this same cDNA probe to obtain a regional localization of this gene. In situ hybridization to normal metaphase chromosomes and to chromosomes from individuals with balanced translocations suggests a regional assignment to chromosome 3q25-26.