Hereditary fructose intolerance in Brazilian patients

Estimation of hereditary fructose intolerance prevalence in the Chinese population

Background

Hereditary fructose intolerance (HFI) caused by aldolase B reduction or deficiency that results in fructose metabolism disorder. The disease prevalence in the Chinese population is unknown, which impedes the formulation of HFI screening and diagnosis strategies.

Materials and methods

By searching a local cohort (Chinese Children’s Rare Disease Genetic Testing Clinical Collaboration System, CCGT) and public databases (ClinVar and Human Gene Mutation Database) and reviewing HFI-related literature, we manually curated ALDOB pathogenic or likely pathogenic (P/LP) variants according to ACMG guidelines. Allele frequency (AF) information from the local database CCGT and the public databases HuaBiao and gnomAD for ALDOB P/LP variants was used to estimate and the HFI prevalence in the Chinese population and other populations by the Bayesian framework. We collected the genotype and clinical characteristics of HFI patients from the CCGT database and published literature to study genotype–phenotype relationships.

Result

In total, 81 variants of ALDOB were curated as P/LP. The estimated Chinese HFI prevalence was approximately 1/504,678, which was much lower than that for non-Finland European (1/23,147), Finnish in Finland (1/55,539), admixed American (1/132,801) and Ashkenazi Jewish (1/263,150) populations. By analyzing the genetic characteristics of ALDOB in the Chinese population, two variants (A338V, A338G) had significantly higher AFs in the Chinese population than in the non-Finland European population from gnomAD (all P values < 0.05). Five variants (A150P, A175D, N335K, R60*, R304Q) had significantly lower AFs (all P values < 0.1). The genotype–phenotype association analyses were based on 68 reported HFI patients from a literature review and the CCGT database. The results showed that patients carrying homozygous variant sites (especially A150P) were more likely to present nausea, and patients carrying two missense variant sites were more likely to present aversion to sweets and fruit (all P values < 0.05). Our research reveals that some gastrointestinal symptoms seem to be associated with certain genotypes.

Conclusion

The prevalence of HFI in the Chinese population is extremely low, and there is no need to add HFI testing to the current newborn screening programs if medical costs are considered. A genetic testing strategy is suggested for early diagnosis of HFI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02487-3.

Inborn errors of metabolism and their impact in paediatric dentistry

The management of paediatric patients with inborn errors of metabolism (IEM) presents an unparalleled challenge for paediatric dentists owing to the multiplex of interrelated dental manifestations and metabolic management necessitating modifications to dental care. Inborn errors of metabolism describe a largely heterogenous group of genetic disorders namely attributable to a single gene defect essential for a specific metabolic pathway. Approximately 400 disorders have been described with an overall incidence of 1 in 5000 live births worldwide. Clinical presentation is classically inconspicuous and insidious in the neonatal period with pathophysiology attributable to accumulation of toxic by-products which interfere with normal function, or insufficient synthesis of essential compounds. This paper aims to discuss the primary oral and maxillofacial manifestations across the scope of inborn errors of metabolism, whilst also considering how metabolic treatment has the propensity to complicate dental management.

Epidemiological aspects of hereditary fructose intolerance: A database study

Hereditary fructose intolerance (HFI) is an inborn error of fructose metabolism of autosomal recessive inheritance caused by pathogenic variants in the ALDOB gene that lead to aldolase B deficiency in the liver, kidneys, and intestine. Patients manifest symptoms, such as ketotic hypoglycemia, vomiting, nausea, in addition to hepatomegaly and other liver and kidney dysfunctions. The treatment consists of a fructose-restricted diet, which results in a good prognosis. To analyze the distribution of ALDOB variants described in patients and to estimate the prevalence of HFI based on carrier frequency in the gnomAD database, a systematic review was conducted to assess ALDOB gene variants among patients with HFI. The prevalence of HFI was estimated from the carrier frequency of variants described in patients, as well as rare variants predicted as pathogenic by in silico tools. The p.(Ala150Pro) and p.(Ala175Asp) variants are the most frequent and are distributed worldwide. However, these variants have particular distribution patterns in Europe. The analysis of the prevalence of HFI showed that the inclusion of rare alleles predicted as pathogenic is a more informative approach for populations with few patients. The data show that HFI has a wide distribution and an estimated prevalence of ~1:10,000.