In-house multiplex ligation-dependent probe amplification assay for citrin deficiency: analytical validation and novel exonic deletions in SLC25A13

The mutation spectrum of SLC25A13 gene in citrin deficiency: identification of novel mutations in Vietnamese pediatric cohort with neonatal intrahepatic cholestasis

BACKGROUND

Citrin deficiency (CD), a disorder caused by mutations in the SLC25A13 gene, may result in neonatal intrahepatic cholestasis. This study was purposely to explore the mutation spectrum of SLC25A13 gene in Vietnamese CD patients.

METHODS

The 292 unrelated CD patients were first screened for four high-frequency mutations by PCR/PCR-RFLP. Then, Sanger sequencing was performed directly for heterozygous or undetected patients. Novel mutations identified would need to be confirmed by their parents.

RESULTS

12 pathogenic SLC25A13 mutations were identified in all probands, including three deletions c.851_854del (p.R284Rfs*3), c.70-63_133del (p.Y24_72Ifs*10), and c.[1956C>A;1962del] (p.[N652K;F654Lfs*45]), two splice-site mutations (IVS6+5G>A and IVS11+1G>A), one nonsense mutations c.1399C>T (p.R467*), one duplication mutation c.1638_1660dup (p.A554fs*570), one insertion IVSl6ins3kb (p.A584fs*585), and four missense mutation c.2T>C (p.M1T), c.1231G>A (p.V411M), c.1763G>A (p.R588Q), and c.135G>C (p.L45F). Among them, c.851_854del (mut I) was the most identified mutant allele (91.78%) with a total of 247 homozygous and 42 heterozygous genotypes of carriers. Interestingly, two novel mutations were identified: c.70-63_133del (p.Y24_72Ifs*10) and c.[1956C>A;1962del] (p.[N652K;F654Lfs*45]).

CONCLUSION

The SLC25A13 mutation spectrum related to intrahepatic cholestasis infants in Vietnam revealed a quite similar pattern to Asian countries' reports. This finding supports the use of targeted SLC25A13 mutation for CD screening in Vietnam and contributed to the SLC25A13 mutation spectra worldwide. It also helps emphasize the role of DNA analysis in treatment, genetic counseling, and prenatal diagnosis.

Case report: Three novel variants on SLC25A13 in four infants with neonatal intrahepatic cholestasis caused by citrin deficiency

Background

Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) is a common clinical phenotype of citrin deficiency in infants. Its phenotype is atypical, so genetic testing is quite necessary for the diagnosis.

Case presentation

We report 4 patients with jaundice and low body weight. Furthermore, the biochemical examination of all showed abnormal liver function and metabolic changes. DNA samples of the patients were extracted and subjected to genetic screening. All candidate pathogenic variants were validated by Sanger sequencing, and CNVs were ascertained by qPCR. The genetic screening revealed 6 variants in 4 patients, and all patients carried compound heterozygous variants of SLC25A13. Importantly, 3 variants were newly discovered: a nonsense mutation in exon17 (c.1803C > G), a frameshift mutation in exon 11(c.1141delG) and a deletion of the whole exon11. Thus, four NICCD patients were clearly caused by variants of SLC25A13. Biochemical indicators of all patients gradually returned to normal after dietary adjustment.

Conclusions

Our study clarified the genetic etiology of the four infants, expanded the variant spectrum of SLC25A13, and provided a basis for genetic counseling of the family. Early diagnosis and intervention should be given to patients with NICCD.

Obstacles to home-based dietary management for caregivers of children with citrin deficiency: a qualitative study

Background

Dietary management is the most important and effective treatment for citrin deficiency, as well as a decisive factor in the clinical outcome of patients. However, the dietary management ability of caregivers of children with citrin deficiency is generally poor, especially in East Asia where carbohydrate-based diets are predominant. The aim of this study was to identify the difficulties that caregivers encounter in the process of home-based dietary management, and the reasons responsible for these challenges.

Results

A total of 26 caregivers of children with citrin deficiency were recruited, including 24 mothers, one father, and one grandmother. Grounded theory was employed to identify three themes (covering 12 sub-themes) related to the dilemma of dietary management: dietary management that is difficult to implement; conflicts with traditional concepts; and the notion that children are only a part of family life. The first theme describes the objective difficulties that caregivers encounter in the process of dietary management; the second theme describes the underlying reasons responsible for the non-adherent behavior of caregivers; the third theme further reveals the self-compromise by caregivers in the face of multiple difficulties.

Conclusions

This study reflects the adverse effects of multi-dimensional contradictions on the adherence of caregivers to dietary management. These findings reveal that the dietary management of citrin deficiency is not only a rational process, rather it is deeply embedded in family, social, and dietary traditions.