Is biliary sludge a stone-in-waiting?

Beyond the definitions of the phenotypic complications of sickle cell disease: an update on management

The sickle hemoglobin is an abnormal hemoglobin due to point mutation (GAG → GTG) in exon 1 of the β globin gene resulting in the substitution of glutamic acid by valine at position 6 of the β globin polypeptide chain. Although the molecular lesion is a single-point mutation, the sickle gene is pleiotropic in nature causing multiple phenotypic expressions that constitute the various complications of sickle cell disease in general and sickle cell anemia in particular. The disease itself is chronic in nature but many of its complications are acute such as the recurrent acute painful crises (its hallmark), acute chest syndrome, and priapism. These complications vary considerably among patients, in the same patient with time, among countries and with age and sex. To date, there is no well-established consensus among providers on the management of the complications of sickle cell disease due in part to lack of evidence and in part to differences in the experience of providers. It is the aim of this paper to review available current approaches to manage the major complications of sickle cell disease. We hope that this will establish another preliminary forum among providers that may eventually lead the way to better outcomes.

Hepatobiliary Manifestations of Sickle Cell Anemia

Sickle cell anemia is one of the common hemoglobinopathies around the world. It results from a single change of one amino acid valine instead of glutamic acid in the hemoglobin beta change. This change leads to polymerization of the hemoglobin when the oxygen saturation is lowered, resulting in deformity of the red blood cells and microvascular occlusion. Sickle cell anemia can affect any part of the body and one of the main organs to be affected is the hepatobiliary system either directly from the sicklening process or indirectly as a result of chronic hemolysis and multiple blood transfusions. This manifests in several clinical conditions which poses diagnostic and therapeutic dilemmas to the treating physicians. These hepatobiliary manifestations will be outlined in this review.

UGT1A1 promoter polymorphisms and the development of hyperbilirubinemia and gallbladder disease in children with sickle cell anemia

Genetic modifiers contribute to phenotypic variability in patients with sickle cell anemia (SCA). The influence of the bilirubin UDP-glucuronosyltransferase (UGT) 1A1 (TA)(n)TAA promoter polymorphism on bilirubin levels and gallbladder disease in SCA was examined using prospectively collected data from the Cooperative Study of Sickle Cell Disease. A total of 324 children with HbSS (median age 6.9 years) had UGT1A1 genotyping; 243 (75%) had common (TA)(6) or (TA)(7) alleles, whereas 81 (25.0%) had variant (TA)(5) or (TA)(8) alleles. The UGT1A1 genotype significantly influenced average bilirubin levels for the common alleles: 6/6 genotype = 2.36 +/- 1.13 mg/dL, 6/7 genotype = 2.90 +/- 1.54 mg/dL, and 7/7 genotype = 4.24 +/- 2.11 mg/dL (P < 0.0001). Thirty-nine percent of children with the 7/7 genotype had documented gallbladder disease, compared with 18.2% with the 6/7 genotype and only 9.9% with the wildtype 6/6 UGT1A1 genotype (P = 0.001). To analyze the (TA)(5) and (TA)(8) variant alleles, three groups were generated, showing increasing bilirubin levels with increasing TA repeats and age. Group 3 (genotypes 6/8, 7/7, and 7/8) had a significantly greater rate of bilirubin change than Groups 1 (genotypes 5/6, 5/7, and 6/6) or 2 (genotype 6/7). These results validate previous smaller studies and confirm that the UGT1A1 promoter polymorphism exerts a powerful influence on bilirubin levels and the development of gallbladder disease in children with SCA. UGT1A1 genotyping should be considered as a screening tool for predicting children most likely to develop gallbladder disease at a young age.

Influence of bilirubin uridine diphosphate-glucuronosyltransferase 1A promoter polymorphisms on serum bilirubin levels and cholelithiasis in children with sickle cell anemia

PURPOSE

Genetic mutations in the uridine diphosphate (UDP)-glucuronosyltransferase 1A (UGT1A) enzyme promoter have been associated with unconjugated hyperbilirubinemia and Gilbert syndrome. The effects of UGT1A promoter polymorphisms on serum bilirubin levels and symptomatic gallstone formation were studied in a cohort of children with sickle cell anemia (SCA).

METHODS

The UGT1A promoter genotype was deterrmined for 115 consecutive children with SCA. Steady-state laboratory parameters and previous cholecystectomy for symptomatic gallstones were recorded retrospectively, then analyzed according to UGT1A genotype.

RESULTS

Children with SCA had a lower frequency of the normal (TA)6 UGT1A promoter allele (0.413) than the abnormal (TA)7 allele (0.461). A previously described shorter (TA)5 allele (frequency 0.074) and longer (TA)8 allele (frequency 0.052) were also observed. Children with the 7/7 UGT1A genotype had a significantly higher mean bilirubin level (5.8 +/- 3.1 mg/dL) than those with the 6/6 (2.4 +/- 0.8 mg/dL) or 6/7 genotype (3.0 +/- 1.1 mg/dL; P < 0.001 by analysis of variance). Patients with the 7/7 genotype were more likely to have previous cholecystectomy (87.5%) than those with the 6/6 (35.7%) or the 6/7 genotype (36.1%; P = 0.002 by chi2).

CONCLUSIONS

Genetic variation in the UGT1A promoter significantly influences serum bilirubin levels and the development of symptomatic cholelithiasis in children with SCA. The UGT1A promoter polymorphisms represent an important nonglobin genetic modifier of clinical disease expression in SCA.

[Cholelithiasis in children with sickle cell disease: experience of a French pediatric hospital]

BACKGROUND

Gallstones are frequently encountered in sickle cell disease. Their complications are difficult to distinguish from vaso-occlusive abdominal pain and they can sometimes threaten the patient's life. The aim of this study was to describe our local experience with cholelithiasis in children with sickle cell disease.

PATIENTS AND METHODS

We analyzed the follow-up records and abdominal sonography results of 185 children with sickle cell anemia, aged zero to 18 years, followed up in Trousseau Children's Hospital (Paris) from 1982 to 1998.

RESULTS

Cholelithiasis was detected in 26 patients. The youngest patient was five years old. Cholelithiasis was discovered because of clinical manifestations in 12 patients. Asymptomatic cholelithiasis patients developed clinical manifestations in 28% cases in a maximum delay of two and a half years after its diagnosis. Laparoscopic cholecystectomy was performed in nine cases and open cholecystectomy in 17 cases. The mean postoperative length of stay was significantly shorter in the group of patients with laparoscopy in comparison with the group with open cholecystectomy. Histologic analysis of the gallbladders noted 85% of acute or chronic cholecystis.

CONCLUSION

We suggest that cholelithiasis should be carefully sought in the presence of abdominal manifestations in sickle cell patients. We recommend that annual abdominal sonography be performed in sickle cell patients as early as seven years of age and elective cholecystectomy be performed on patients with cholelithiasis.