Chromosomal deletions detected at amniocentesis

Area of Science:

• Genetics
• Prenatal Diagnosis
• Medical Science

Background:

• Chromosomal deletions are significant genetic abnormalities that can lead to various developmental issues.
• Amniocentesis is a common prenatal diagnostic procedure for detecting chromosomal abnormalities.

Purpose of the Study:

• To determine the incidence, prenatal and postnatal findings, and ascertainment methods for chromosomal deletions identified through amniocentesis.
• To analyze the characteristics and associated factors of chromosomal deletions diagnosed prenatally.

Main Methods:

• A retrospective review of 31 cases with chromosomal deletions detected by amniocentesis between 1987 and 2012.
• Data collection included deletion type, location, reasons for amniocentesis, maternal and gestational age, fetal karyotypes, inheritance, and prenatal findings.

Main Results:

• Chromosomal deletions occurred in 31 of 33,305 amniocenteses, with a mean maternal age of 32.1 years and gestational age of 21.0 weeks.
• Abnormal ultrasound findings (61.3%) and advanced maternal age (35.5%) were primary reasons for amniocentesis. Deletions were predominantly de novo (92.6%) and more frequent in females.
• Chromosomes 5 and 18 were most commonly affected (12.9% each). Terminal deletions (74.2%) were more prevalent than interstitial deletions.

Conclusions:

• Chromosomal deletions identified via amniocentesis are more common in females and often involve chromosomes 5p and 18q.
• Advanced maternal age, abnormal ultrasound, and abnormal maternal serum screening are key factors for prenatal diagnosis of chromosomal deletions.
• Prenatal ultrasound is crucial for diagnosing terminal deletions, highlighting its importance in genetic counseling and management.