Major congenital malformations in Down syndrome

Area of Science:

• Medical Genetics
• Developmental Biology
• Pediatrics

Background:

• Down syndrome (DS) is associated with a spectrum of congenital anomalies.
• Understanding the specific malformation risks in DS is crucial for early diagnosis and management.
• Previous studies have identified some common malformations in DS, but comprehensive risk analysis across multiple malformation types is needed.

Purpose of the Study:

• To quantify the risk of 23 major congenital malformations in infants with Down syndrome (DS).
• To compare malformation prevalence in DS infants with non-DS infants using data from three congenital malformation registers.
• To investigate the influence of maternal age and sex on malformation occurrence in DS.

Main Methods:

• Retrospective analysis of major malformations in 5,581 infants with Down syndrome (DS).
• Comparison of birth prevalence rates for 23 malformations between DS and non-DS infants.
• Statistical analysis to determine risk ratios and investigate demographic factors.

Main Results:

• DS infants showed substantially increased risks (3-300 times) for annular pancreas, cataracts, duodenal atresia, megacolon, small choanal atresia, esophageal atresia, anal atresia, small bowel atresia, preaxial polydactyly, and omphalocele.
• Elevated risk ratios (3-5) were observed for cleft palate, cleft lip/palate, and limb deficiencies.
• No increased risk was found for neural tube defects, hydrocephaly, microtia, renal agenesis/dysgenesis, hypospadias, or non-preaxial polydactyly. Cardiac defects occurred in 26% of DS infants.
• Younger maternal age (<25 years) was linked to increased megacolon risk, while older maternal age showed a trend towards increased esophageal/anal atresia risk.
• Teenage mothers had a decreased risk for cardiac defects in DS infants, particularly endocardial cushion and ventricular septal defects.

Conclusions:

• Down syndrome is associated with a highly variable risk profile for congenital malformations, with some conditions being exceptionally common.
• Specific malformations like annular pancreas, duodenal atresia, and certain gastrointestinal atresias represent significant risks in DS.
• Maternal age influences the risk of certain malformations in DS infants, highlighting potential etiological factors and the need for tailored prenatal counseling.