Survival of trisomy 18 cases in Japan.

The prognosis of trisomy 18 is lethal, but recently some long-term survival cases have been recognized. We report here the mortality rate of trisomy 18 based on our hospital data and sporadically published reports in Japan. We collected the 7 previously published reports of mortality and 31 cases from our hospital data with trisomy 18. Our data pool comprised a total of 179 cases of trisomy 18 from 8 institutions. The mortality rates within 24 hours, 7, 28, 60, 180, and 365 days from birth were 14.84% (19/128), 31.01% (40/129), 56.25% (72/128), 64.08% (66/103), 82.17% (106/129), and 90.90% (140/154), respectively. Fourteen of the 154 patients (9.09%) survived for more than 1 year. The Kaplan-Meier survival curves from 78 patients of 5 institutes suggest that trisomy 18 children who have survived over 7 months after birth may have a high probability of long-term survival. We should recognize not only that about 50% of infants with trisomy 18 die within 1 month after birth, but also that about 10% of patients survive over 1 year in Japan. These findings comprise Asia's first clinical statistics concerning trisomy 18, in which the data were collected from multiple institutions. This evidence is valuable in order to perform genetic counseling concerning the natural history of trisomy 18 not only in Japan but also in other countries.