613 CLUSTER OF TRISOMY 13 LIVE BIRTHS
SIR,-We saw 6 babies with a karyotype of 47, XY or XX, +13 in 10 weeks between Aug. 20, and Oct. 31, 1977. Parents of 5 of these infants were all under 30 years old, and none had a history of exposure to radiation, drugs, or illness during pregnancy. Previous reproductive histories were unremarkable. All the families live in Maryland, though2 of the deliveries were in Washington, D.C. The
frequency of trisomy-13 among live births is about
1 in
14000.’- There-were approximately 46 000 live births in so 3 or 4 cases of trisomy-13’ might be in expected a year. Lately the yearly average for trisomy-13 has been 0.54 at this institution. We are unaware of any change in the referral pattern of local physicians that would account for the increased frequency. Furthermore the incidence of trisomy-21 has not changed during the past 24 months.
Maryland (1976)
Warburton et al.3 reported an increased frequency of trisomies in New York City (not confined to trisomy-13) among spontaneous abortuses and fetuses subjected to prenatal diagnosis. There was a four-fold increase in both these groups, and all were conceived in December, 1976, or January, 1977. Last menstrual periods of the mothers of all our patients correspond to this time also. We have no clues as to a common denominator, and report this cluster to see if a similar increase in trisomy-13 live births during the same time period has been observed at other centres. Division of Genetics,
that in this small group of patients the duration of postoperative hospital stay was a valid index of morbidity; it was determined only by fitness for discharge.
Wright
Department of Pediatrics, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, U.S.A.
G. S. PAI DAVID VALLE GEORGE THOMAS
Children’s Hospital National Medical Center, Washington, D.C.
KENNETH ROSENBAUM
We thank Professor Dudley (Jan. 28, p. 213) for his helpful comments but feel that selection of the right statistical technique for handling these data is difficult. Our series now comprises 47 comparable patients, and the median hospital stay of 21 nutritionally normal patients was 17 days (range 11-25) while that of the 26 nutritionally depleted patients was 27 days (range 12-60). A non-parametric (Wilcoxon) test reveals this difference to be significant (P
SIR,-We saw 6 babies with a karyotype of 47, XY or XX, +13 in 10 weeks between Aug. 20, and Oct. 31, 1977. Parents of 5 of these infants were all under 30 years old, and none had a history of exposure to radiation, drugs, or illness during pregnancy. Previous reproductive histories were unremarkable. All the families live in Maryland, though2 of the deliveries were in Washington, D.C. The
frequency of trisomy-13 among live births is about
1 in
14000.’- There-were approximately 46 000 live births in so 3 or 4 cases of trisomy-13’ might be in expected a year. Lately the yearly average for trisomy-13 has been 0.54 at this institution. We are unaware of any change in the referral pattern of local physicians that would account for the increased frequency. Furthermore the incidence of trisomy-21 has not changed during the past 24 months.
Maryland (1976)
Warburton et al.3 reported an increased frequency of trisomies in New York City (not confined to trisomy-13) among spontaneous abortuses and fetuses subjected to prenatal diagnosis. There was a four-fold increase in both these groups, and all were conceived in December, 1976, or January, 1977. Last menstrual periods of the mothers of all our patients correspond to this time also. We have no clues as to a common denominator, and report this cluster to see if a similar increase in trisomy-13 live births during the same time period has been observed at other centres. Division of Genetics,
that in this small group of patients the duration of postoperative hospital stay was a valid index of morbidity; it was determined only by fitness for discharge.
Wright
Department of Pediatrics, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, U.S.A.
G. S. PAI DAVID VALLE GEORGE THOMAS
Children’s Hospital National Medical Center, Washington, D.C.
KENNETH ROSENBAUM
We thank Professor Dudley (Jan. 28, p. 213) for his helpful comments but feel that selection of the right statistical technique for handling these data is difficult. Our series now comprises 47 comparable patients, and the median hospital stay of 21 nutritionally normal patients was 17 days (range 11-25) while that of the 26 nutritionally depleted patients was 27 days (range 12-60). A non-parametric (Wilcoxon) test reveals this difference to be significant (P
