Chromosomal deletions detected at amniocentesis.
OBJECTIVE
The aim of this study is to present the incidence, prenatal and postnatal findings, and modes of ascertainment in chromosomal deletions detected at amniocentesis.


METHODS
We reviewed all the cases with chromosomal deletions, which were detected by amniocentesis in Mackay Memorial Hospital, Taipei, Taiwan, between January 1987 and December 2012. Data on the locations and types of deletion, reasons for performing amniocentesis, maternal age, gestational age at amniocentesis, fetal karyotypes, inheritance of deletions, and relative prenatal findings were collected.


RESULTS
Amniocentesis was performed in 33,305 cases within this period of time. Among these, 31 cases of chromosomal deletions were considered for the study. The mean gestational age at amniocentesis was 21.0 weeks (range from 15 weeks to 32 weeks) and the mean maternal age at amniocentesis was 32.1 years (range from 26 years to 37 years). Nineteen cases (61.3%) manifested fetal structural abnormalities on ultrasound, nine (29.0%) presented no ultrasound abnormalities, and three had an unknown status. The main modes of ascertainment included abnormal ultrasound findings in 10 cases (32.2%), advanced maternal age in 11 cases (35.5%), abnormal maternal serum screening results in six cases (19.6%), and other reasons in four cases (13.0%). Of the 27 cases with known inheritance, the deletion was inherited in two (6.6%) and de novo in 25 (92.6%). Males accounted for 11 (35.5%) and females for 20 (64.5%) cases. Chromosomal deletions are more often to occur in chromosomal 5(4 cases, 12.9%), chromosomal 18 (4 cases, 12.9%), chromosomal 4 (3 cases, 9.7%), chromosomal 7 (3 cases, 9.7%), chromosomal 10 (3 cases, 9.7%), chromosomal 11 (3 cases, 9.7%), and chromosomal 1 (2 cases, 6.5%). There were four cases of chromosomal mosaicism: two involved chromosome 5, one involved chromosome 10, and one involved chromosome 18. Twenty-three cases (74.2%) had terminal deletions and the other eight cases (26.7%) had interstitial-type deletions.


CONCLUSIONS
In summary, we have presented the results of prenatal diagnosis for chromosomal deletions using amniocentesis. Chromosomal deletions are more likely to occur in females and more often in chromosomal 5p and 18q. Prenatal diagnosis at amniocentesis is frequently associated with advanced maternal age, abnormal ultrasound findings, and abnormal maternal serum screening. The frequency of ascertainment in chromosome deletion seems to be directly correlated with advanced maternal age and abnormal ultrasound findings. In cases with terminal deletions, prenatal ultrasound plays a more important role for prenatal diagnosis.
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan. Electronic address: alflelin@yahoo.com.tw.
Chen-Ju
CJ
Lin
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan; Department of Medical Research, Mackay Memorial Hospital, Taipei, Taiwan; Department of Biotechnology, Asia University, Taichung, Taiwan; School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan; Institute of Clinical and Community Health Nursing, National Yang-Ming University, Taipei, Taiwan; Department of Obstetrics and Gynecology, National Yang-Ming University, Taipei, Taiwan.
Chih-Ping
CP
Chen
School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan; Department of Obstetrics and Gynecology, Kanru Clinic, Taipei, Taiwan.
Shu-Chin
SC
Chien
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
Chen-Chi
CC
Lee
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
Dai-Dyi
DD
Town
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
Wen-Lin
WL
Chen
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
Li-Feng
LF
Chen
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
Meng-Shan
MS
Lee
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
Chen-Wen
CW
Pan
Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei, Taiwan.
Ku-Chien
KC
Lin
Department of Pediatrics, Kanru Clinic, Taipei, Taiwan.
Tze-Tien
TT
Yeh
D059786:Abnormal Karyotype; D000328:Adult; D000649:Amniocentesis / Q000706:statistics & numerical data*; D002872:Chromosome Deletion; D025063:Chromosome Disorders / Q000175:diagnosis* / Q000453:epidemiology; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics; D006801:Humans; D015994:Incidence; D008297:Male; D008423:Maternal Age; D009030:Mosaicism / Q000706:statistics & numerical data*; D011247:Pregnancy; D013624:Taiwan / Q000453:epidemiology
chromosome; deletion; prenatal diagnosis; ultrasound