Hydrolethalus syndrome.

Hydrolethalus syndrome is a lethal malformation syndrome with hydrocephalus, micrognathia, and polydactyly as the most obvious symptoms.Many of the patients are stillborn and the survival of the others has not been long.Hydrolethalus syndrome was recognised as a consequence of a study on Meckel syndrome in Finland.' Apart from the first 28 cases, there are another 28 Finnish cases that we know about.This means an incidence of at least 1:20 000 in Finland.A few reports of the syndrome have been published from elsewhere.26 Clinical fidings (table)PREGNANCY AND BIRTH Today, many cases are recognised during pregnancy by ultrasound, even in the case of the first affected of the family.7 Hydrocephalus with absent midline structures of the brain is seen.The size of the head may correspond to the gestational age, especially before 20 weeks, but there is usually obvious dis- crepancy with the size of the trunk of the fetus, which is small for dates.Later, the pregnancy is complicated by polyhydramnios and often preterm delivery.About 70% of the patients are stillborn.Those born alive survive a few minutes to a few hours at most.