A Diagnostic Survey of Newborns for Chromosomal Analysis: Karyotypes in Congenital Anomalies and Dysmrphism

Suh, Eun Ah; Sung, In Kyung; Lee, Byung Chul

Abstract

Clinical characteristics of 336 infants referred for chromosomal study during neonatal period from Jan. 1985 to Dec. 1994 to the cytogenetic laboratory of St. Mary's Hospital, Catholic University Medical College were reviewed. Karyotypes were analysed from peripheral blood lymphocyte cultures and G-banding was carried out. A thorough survey of the clinical reasons for chromosomal analysis, prevalence of chromosomal abnormalities in each disease category, and the patterns of chromosomal aberrations were done. The results were as follows, 1) Down syndrome was the most common indication for chromosome analysis in the newborn period, consisting of 37.8 % of all cases referred. Other indications included skeletal anomaly, multi-organ anomalies, cleft lip/palate, ambiguous genitalia, odd looking face, gastrointestinal anomaly, central nervous system anomaly, and Turner syndrome. 2) Overall in 42.9 percent of cases referred, chromosomal abnormalities was found. 3) 1'he percentage of final diagnosis in suspected Down syndrome was 85.0 #96. Overall, of the non-Down syndrome cases, 16.7 96 was given a definitive diagnosis of chromosomal abnomality. In each disease category, 57.1 % of suspected Turner syndrome and 37.2 % of multi-organ anomalies had been proved having chromosomal abnormalities. The percentages of chromosomal aberrations in isolated odd looking face, ambiguous genitalia, and skeletal anomaly were relatively low, around 5 %. None of the newborns referred because of cleft lip/palate, congenital anomalies of gastrointestinal tract or central nervous system had abnormal karyotype. 4) 95.1 % of all cases diagnosed to have chromosomal abnormality had autosomal aberrations, the remainder 4.9 % had sex chromosomal aberrations. 5) Trisomy 21 was the most common numerical aberrations of autosomes, consisting of 87.5 % and trisomy 18, trisomy 13, and mosaicism was 7.1 %, 3.6 96 and 1.8 % of total. 6) 90.7 % of Down syndrome were due to trisomy 21, the rest being translocation (7.4 %) and mosaicism (1.9 %).