Congenital chloride diarrhoea: case report and review of the literature

Magnetic resonance imaging in the prenatal diagnosis of congenital diarrhea

OBJECTIVE

Congenital diarrhea is very rare, and postnatal diagnosis is often made once the condition has caused potentially lethal fluid loss and electrolyte disorders. Prenatal detection is important to improve the immediate neonatal prognosis. We aimed to describe the prenatal ultrasound and magnetic resonance (MRI) imaging findings in fetuses with congenital diarrhea.

METHODS

The study reports the pre- and postnatal findings in four fetuses that presented with generalized bowel dilatation and polyhydramnios. We analyzed the fetal ultrasound and MRI examinations jointly, then compared our provisional diagnosis with the amniotic fluid biochemistry and subsequently with the neonatal stool characteristics.

RESULTS

In each of the four cases an ultrasound examination between 22 and 30 weeks' gestation showed moderate generalized bowel dilatation and polyhydramnios suggesting intestinal obstruction. MRI examinations performed between 24 and 32 weeks' gestation confirmed that the dilatation was of gastrointestinal (GI) origin, with a signal indicating intraluminal water visible throughout the small bowel and colon. The expected hypersignal on T1-weighted sequences characteristic of physiological meconium was absent in the colon and rectum. This suggested that the meconium had been completely diluted and flushed out by the water content of the bowel. The constellation of MRI findings enabled a prenatal diagnosis of congenital diarrhea. The perinatal lab test findings revealed two cases of chloride diarrhea and two of sodium diarrhea.

CONCLUSION

Congenital diarrhea may be misdiagnosed as intestinal obstruction on prenatal ultrasound but has characteristic findings on prenatal MRI enabling accurate diagnosis; this is important for optimal neonatal management.

SLC26A3 mutations in congenital chloride diarrhea

Congenital chloride diarrhea (CLD) is an autosomal recessive disorder of intestinal electrolyte absorption. It is characterized by persistent secretory diarrhea resulting in polyhydramnios and prematurity prenatally, and dehydration, hypoelectrolytemia, hyperbilirubinemia, abdominal distention, and failure to thrive immediately after birth. CLD is caused by mutations in the solute carrier family 26, member 3 gene (SLC26A3, alias CLD or DRA), which encodes a Na+-independent Cl-/HCO3- (or OH-) exchanger. SLC26A3 is a member of the SLC26 sulfate permease/anion transporter family and it is expressed mainly in the apical brush border of intestinal epithelium. The only extraintestinal tissues showing SLC26A3 expression are eccrine sweat glands and seminal vesicles. A wide variety of different mutations in the SLC26A3 gene have been associated with CLD with no apparent evidence of phenotype-genotype correlation. The clinical course of CLD, however, is variable and may rather depend on environmental factors and compensatory mechanisms than mutations. In this report, we present a summary of all published and two novel SLC26A3 mutations and polymorphisms, and review them in the context of their functional consequences and clinical implications.

Genetic background of congenital chloride diarrhea in high-incidence populations: Finland, Poland, and Saudi Arabia and Kuwait

Congenital chloride diarrhea (CLD) is an inherited intestinal disorder caused by mutations in the down-regulated in adenoma gene. In Finland, the disease is prevalent because of a founder effect, and all but one of the CLD-associated chromosomes carry the same mutation, V317del. In Poland, another area with a high incidence of CLD, as many as seven different mutations have been detected so far. A third known cluster of CLD, around the Persian Gulf, has not been genetically studied. We studied the allelic diversity of CLD in Poland, in Saudi Arabia and Kuwait, and in three isolated families from North America and Hong Kong. Altogether, eight novel mutations were identified, making a total of 19 known CLD gene mutations. The Polish major mutation I675-676ins was found in 47% of the Polish CLD-associated chromosomes. Haplotype analysis and clustering of the I675-676ins mutation supported a founder effect and common ancestral origin. As in Finland, a major founder effect was observed in Arab patients: 94% of the CLD-associated chromosomes carried a nonsense mutation, G187X, which occurred in either a conserved ancestral haplotype or its derivative. Our data confirm that the same locus is mutated in all cases of CLD studied so far. In Poland, a relatively common founder mutation is likely to highlight a set of rare mutations that would very rarely produce homozygosity alone. This suggests that mutations in the CLD locus are not rare events. Although the disease is thought to be rare, undiagnosed patients may not be uncommon.

Congenital chloride diarrhoea: a prenatal differential diagnosis of small bowel atresia

We compared ultrasound findings and pre- and postnatal clinical signs in 8 patients with congenital chloride diarrhoea and 14 with small bowel atresia diagnosed in 1977-1991 in order to evaluate the possibility of a prenatal distinguishing diagnostic sign. In the patients with congenital chloride diarrhoea the pregnancy was complicated by marked polyhydramnios, the symphysis-fundus distance exceeded + 2 SD before gestational week 31 and the fetus displayed normal peristalsis in extensively dilated intestines and the "frog position". In the patients with small bowel atresia the symphysis-fundus distance was normal before gestational week 31 and the fetus displayed increased peristalsis in a few dilated intestinal loops.

Aetiology of chronic diarrhoea in children: experience at King Khalid University Hospital, Riyadh, Saudi Arabia

Forty-eight cases of chronic diarrhoea in children seen at King Khalid University Hospital over a 5-year period were analysed. The mean age at presentation was 1.8 years (range 0.08-10 years); 34 were boys and 14 girls. Forty-four patients were Saudi and four were non-Saudi Arabs. Most children presented with failure to thrive and pallor. The aetiological factors identified were: the post-gastro-enteritis syndrome with or without lactose intolerance in 16 (33%); coeliac disease in ten (21%); congenital chloride diarrhoea in five (10%); glucose-galactose malabsorption and acrodermatitis enteropathica, each in three (6%); ulcerative colitis, intestinal lymphangiectasia, cow's milk protein intolerance and ataxia telangiectasia, each in two (4%); and giardiasis, immune deficiency and cystic fibrosis, each in one (2%). Five children died.