SNP Shot: Genomic Insights

An abdominal wall defect is a birth condition characterized by an opening in the abdominal area, allowing internal organs to protrude. The size of this opening can vary and is typically identified early in pregnancy, between 10 and 14 weeks. The two primary types are omphalocele and gastroschisis. Omphalocele presents as an opening at the umbilical cord's insertion point on the abdomen. The protruding organs (commonly intestines, stomach, and liver) are contained within the umbilical cord and covered by its protective membrane. Gastroschisis, conversely, involves a defect in the abdominal wall, usually located to the right of the umbilical cord. Through this opening, the large and small intestines typically protrude, although other organs may also be exposed. In gastroschisis, the organs are not covered by a protective membrane.

Babies with omphalocele may experience slow growth before birth (intrauterine growth restriction) and premature delivery. They are also more likely to have other birth defects, such as congenital heart defects. Lung underdevelopment is frequently seen in conjunction with omphalocele, as the abdominal organs' usual position supports chest wall development. When these organs are displaced, the chest cavity may not form properly, leading to reduced lung capacity. This can result in respiratory insufficiency, requiring mechanical ventilation. In rare cases, infants with omphalocele who experience breathing issues may develop recurrent lung infections or asthma later in life. Gastrointestinal problems, such as gastroesophageal reflux and feeding difficulties, are also common and can persist even after omphalocele treatment. Larger omphaloceles, or those accompanied by other health problems, have a higher association with fetal death than isolated cases.

Omphalocele is associated with several genetic syndromes. Almost half of the babies with omphalocele have a trisomy, caused by an extra copy of a chromosome in each cell. Up to a third of individuals born with omphalocele have Beckwith-Wiedemann syndrome, a genetic condition. These individuals may exhibit additional signs and symptoms related to these genetic conditions.

Gastroschisis, on the other hand, is rarely associated with other birth defects, chromosome abnormalities, or genetic conditions. However, many infants with gastroschisis experience intrauterine growth restriction, resulting in small size at birth, and many are born prematurely.

In gastroschisis, the exposed organs lack a protective membrane and are susceptible to damage from direct contact with amniotic fluid in the womb. This contact can trigger immune and inflammatory responses that harm the intestinal tissue. Compression of the exposed organs at the abdominal wall opening late in fetal development can also contribute to organ damage. Intestinal damage often impairs peristalsis (muscle contractions that move food through the digestive tract) in children with gastroschisis. This impairment usually improves within a few months as intestinal muscle contractions normalize. In rare instances, children with gastroschisis may develop intestinal atresia (narrowing or absence of a portion of the intestine) or intestinal twisting. These intestinal malformations can lead to digestive problems, further intestinal tissue loss, and short bowel syndrome (resulting from missing sections of the small intestine, causing dehydration and poor nutrient absorption). Intravenous feedings (parenteral nutrition) may be required, depending on the condition's severity.

The long-term health of an individual with gastroschisis largely depends on the extent of intestinal damage before birth. If the abdominal wall defect is repaired and normal intestinal function is restored, most individuals experience no further health issues related to the repaired defect.

Inheritance:

Most cases of abdominal wall defects occur sporadically, meaning they arise without a family history of the condition. Multiple genetic and environmental factors likely contribute to the risk of developing this disorder. When an abdominal wall defect, most commonly omphalocele, is part of a genetic condition, it is inherited according to the inheritance pattern of that specific condition.