The effect of neonatal jaundice on biotinidase activity

Incidence of Inborn Errors of Metabolism and Endocrine Disorders Among 40965 Newborn Infants at Riyadh Second Health Cluster of the Ministry of Health Saudi Arabia

Inborn errors of metabolism (IEM) and endocrine disorders are common genetic conditions in the Saudi population with the incidence rate often underestimated. Newborn screening (NBS) using various disease panels provides the first line in the early detection and intervention among infants with a high risk of IEM. Here we aim to assess the incidence of screening disorders and provide an overview of the NBS program at the Ministry of Health Tertiary Care King Fahad Medical City. Dried blood spots (DBS) from 40,965 newborn infants collected on the second day after birth were analyzed for 20 disorders. The total number of positive screen ("repeat") samples over 10 years was about 1% (n = 382/40,965). The true positive result rate was 15.3% (n = 46/301) with the recall rates of individual disorders ranging from 0.26% (95% CI, 0.17-0.69) to 2.6% (95% CI, 2.19-3.05). The false positive result rate was 84.7% (n = 255/301) with biotinidase activity found to be the most common cause of the second sample repeat. The overall incidence of the screened diseases was 1:891 (95% CI, 11.61-12.47). CH and CAH are the most prevalent among endocrine disorders with an incidence of 1:4097 (95% CI, 2.19-3.05), and PA and ASA among the IEM with an incidence of 1:10,241 (95% CI, 0.09-0.95). In summary, we provide updated data and our experience on the incidence of various IEM and endocrine disorders among the Saudi population, highlight the role of false positive results of biotinidase activity that can increase the recall rate and lead to overestimation of the incidence data, and recommend multicenter studies to achieve a successful national NBS program.

Clinical, biochemical and genotypical characteristics in biotinidase deficiency

OBJECTIVES

Hypotonia, lethargy, eczema, alopecia, conjunctivitis, ataxia, hearing loss, optic atrophy, cognitive retardation, and seizures can occur in patients with biotinidase deficiency, and it is inherited as autosomal recessive. The aim of this study was to evaluate the cases followed up with the diagnosis of biotinidase deficiency in our unit, in terms of clinical, biochemical and genetic analyses.

METHODS

A total of 112 cases followed up in our centre with the diagnosis of biotinidase deficiency between August 2018-September 2020 were included in the study. Data were collected retrospectively.

RESULTS

A total of 112 cases (55.4% male, mean age: 2.2 ± 2.8 years) diagnosed with biotinidase deficiency were evaluated. Diagnoses were made by newborn screening in 90.2% of the cases, by family screening in 4.5%, and by investigating symptoms in 5.4%. The most frequently (27.5%) detected mutations were c.1330G>C (p.D444H)/c.1330G>C (p.D444H) homozygous mutation, followed by (13.0%) c.1330G>C (p.D444H)/c.470G>A (p.R157H) compound heterozygous mutation, and (13.0%) c.470G>A (p.R157H)/c.470G>A (p.R157H) homozygous mutation. Biotinidase enzyme levels were found to be higher in patients with the p.D444H homozygous mutation than patients with other mutations. Biotin treatment was started in all patients with enzyme deficiency.

CONCLUSIONS

Since the treatment is inexpensive and easily available, it is vital to detect this disease before symptom onset, especially findings related to the central nervous system, hearing and vision loss. In patients diagnosed with enzyme deficiency, the diagnosis should be definitively confirmed by genetic analysis.

Neonatal screening parameters in infants with congenital Cytomegalovirus infection

Congenital Cytomegalovirus infection (cCMV) is the most common cause of congenital infections worldwide that can cause long-term impairment (LTI). The metabolic alterations due to cCMV are largely unknown. This study aims to assess the metabolites included in the neonatal screening in relation to cCMV and cCMV outcome, allowing the identification of prognostic markers for clinical outcome. Essential amino acids, hormones, carnitines and enzymes from Dried Blood Spots (DBS) were analyzed of 102 children with cCMV and 179 children without cCMV, and they were related to symptoms at birth and LTI at 6years of age. In this cohort, the neonatal screening parameters did not change in relation to cCMV, nor to symptoms at birth or LTI. However, metabolic changes were observed in children born preterm, with lower concentrations of essential amino acids in premature infants with cCMV compared to premature controls. Finally, a higher concentration of palmytoilcarnitine (C16) in the group with higher viral load was observed. Though these data demonstrate limitations in the use of neonatal screening data as predictors for long-term cCMV outcome, the metabolism of preterm neonates with cCMV merits further evaluation.

Carvalho MR, S. Fonseca PA, S. Camelo J, M. Ribeiro E, F. V. de Medeiros P, M. Lourenço C, F. M. de Souza C, Boy R, Félix TM, M. Bittar C, L. C. Pinto L, C. Neto E, J. Blom H, D. Schwartz IV. Biotinidase deficiency: Genotype-biochemical phenotype association in Brazilian patients

Introduction

The association between the BTD genotype and biochemical phenotype [profound biotinidase deficiency (BD), partial BD or heterozygous activity] is not always consistent. This study aimed to investigate the genotype-biochemical phenotype association in patients with low biotinidase activity.

Methods

All exons, the 5'UTR and the promoter of the BTD gene were sequenced in 72 Brazilian individuals who exhibited low biotinidase activity. For each patient, the expected biochemical phenotype based on the known genotype was compared with the observed biochemical phenotype. Additional non-genetic factors that could affect the biotinidase activity were also analysed.

Results

Most individuals were identified by neonatal screening (n = 66/72). When consecutive results for the same patient were compared, age, prematurity and neonatal jaundice appeared to affect the level of biotinidase activity. The biochemical phenotype at the time of the second blood collection changed in 11/22 patients compared to results from the first sample. Three novel variants were found: c.1337T>C (p.L446P), c.1466A>G (p.N489S) and c.962G>A (p.W321*). Some patients with the same genotype presented different biochemical phenotypes. The expected and observed biochemical phenotypes agreed in 68.5% of cases (concordant patients). The non-coding variants c.-183G>A, c.-315A>G and c.-514C>T were present in heterozygosis in 5/17 discordant patients. In addition, c.-183G>A and c.-514C>T were also present in 10/37 concordant patients.

Conclusions

The variants found in the promoter region do not appear to have a strong impact on biotinidase activity. Since there is a disparity between the BTD genotype and biochemical phenotype, and biotinidase activity may be affected by both genetic and non-genetic factors, we suggest that the diagnosis of BD should be based on more than one measurement of plasma biotinidase activity. DNA analysis can be of additional relevance to differentiate between partial BD and heterozygosity.

Neonatal screening for profound biotinidase deficiency in the Netherlands: consequences and considerations

Biotinidase deficiency is a rare inherited metabolic disorder that can cause severe neurological symptoms. To prevent severe clinical presentations, it was included in the Dutch neonatal screening programme in 2007. Since then the number of cases detected has been high. This study set out to describe the incidence of the disease, the clinical and demographic characteristics of the neonates identified and the type of mutations found. In the south-western Netherlands, 304 982 neonates were screened between 2007 and 2012; and 92 were identified for further testing. Confirmatory testing revealed 6 (7%) with a profound biotinidase deficiency (<10% enzyme activity), 44 (48%) with a partial deficiency (10-30%) and 42 (46%) with normal activity (>30%). All six patients whose profound deficiency was confirmed had enzyme activities below 15% on neonatal screening. Mutation analysis was performed in 61 neonates: 5 'profound', 35 'partial' and 21 'normal'. All five 'profound' cases had two severe mutations. Comparison with the northern Netherlands showed that the frequency and types of mutation were representative for the Netherlands as a whole. The most common mutation detected was c.[1330G>C] (p.(Asp444His); 34%), which is considered to be mild, followed by three severe mutations c.[1368A>C], c.[1595C>T] and c.[1330G>C;511G>A]. Seven new mutations were identified. We conclude that neonatal screening for profound biotinidase produces a high number of false positives. Biotinidase deficiency was profound in less than 10% of cases identified. As biotinidase activity lay below 15% on neonatal screening in all such cases, the screening threshold might be reduced to 15%.

Comparison of Spectrophotometric and Fluorimetric Methods in Evaluation of Biotinidase Deficiency

Background

Biotin, a water-soluble vitamin, is used as a co-factor by enzymes involved in carboxylation reactions. Biotinidase (BTD) catalyzes the recycling of biotin from endogenous and dietary sources. Biotinidase deficiency (BD) is an autosomal recessively inherited disorder of biotin recycling that is associated with neurologic and cutaneous consequences when untreated. The aim of the study was to compare the results of spectrophotometric and fluorimetric methods, as well as to evaluate the advantages and disadvantages of both methods in current research practices.

Methods

Study group was chosen among the BD suspected newborn, children and parents (n = 52) who applied to Hacettepe University Pediatric Metabolism Unit.

Results

BTD activity is stable for 2 hours at room temperature and at 4 °C, and for 4 months at –20 °C and –80 °C. Genetic and clinical results showed that 25% of the total number of patients had complete BD which was treated with 10 mg/day biotin, while 15.38% of the patients had partial BD, and they were prescribed biotin 5 mg/day. The area under the ROC curve was 0.960±0.25 and 0.927± 0.41 for the fluorimetric and spectrophotometric method, respectively. Fluorimetric method showed 100% sensitivity and 97% specificity, whereas spectrophotometric method showed 90.5% sensitivity and 93.7% specificity.

Conclusions

Fluorimetric method is superior to the spectrophotometric method due to higher sensitivity and specificity.

Biotinidase deficiency: clinical and genetic studies of 38 Brazilian patients

Background

Biotinidase deficiency (BD) is an inborn error of metabolism in which some genetic variants correlate with the level of enzyme activity. Biotinidase activity, however, may be artifactually low due to enzyme lability, premature birth, and jaundice; this hinders both phenotypic classification and the decision to implement therapy. This study sought to characterize the clinical and genetic profile of a sample of Brazilian patients exhibiting reduced biotinidase activity.

Methods

This observational, multicenter study used a convenience sampling strategy, with sequencing of exons 2, 3, and 4 of the BTD gene.

Results

The sample comprised 38 individuals with biochemical phenotypes defined a priori on the basis of biotinidase activity in serum/plasma (2 with profound deficiency, 9 with partial deficiency, 15 heterozygous, 1 borderline between partial deficiency and heterozygosity, 2 borderline between heterozygous and normal) or dried blood spot sample (n = 9, all with unspecified deficiency). Most patients were from Southern Brazil (n = 29/38) and were identified by neonatal screening (n = 33/38). Parental consanguinity was reported in two cases. The most commonly found genetic variants were c.1330G > C (p.D444H), c.755A > G (p.D252G), and c.[511G > A;1330G > C] (p.[A171T;D444H]), with allele frequencies of 50%, 9.4%, and 5.4% respectively. Three novel pathogenic variants were identified (c.119 T > C or p.L40P, c.479G > A or p.C160Y, and c.664G > A or p.D222N). Twenty-nine patients had two pathogenic variants detected (with cis/trans status ascertained in 26/29), six had only one variant, and three had no pathogenic variants detected. Genotyping confirmed the original phenotypic classification based on enzyme activity in 16/26 cases. Three polymorphic variants were identified in control individuals, of which two were nonpathogenic (c.1171C > T or p.P391S and c.1413 T > C or p.C471C, with a frequency of 1.5% and 5.5% respectively) and one pathogenic (c.1330G > C, frequency 4%).

Conclusions

Our findings suggest that partial BD is the most common form of BD in Brazil, and expand current knowledge on the allelic heterogeneity of this condition.

High incidence of partial biotinidase deficiency cases in newborns of Greek origin

Biotinidase deficiency (BTD) is an inherited disorder with severe clinical manifestations if not treated early. 63,119 neonates were tested for BTD according to a 3-step protocol. Biotinidase activity was initially estimated through standard colorimetric method on dried blood spots, then the suspected samples were subjected to molecular analysis of the BT gene and determination of BT activity in serum through an HPLC method. 14 infants with partial BTD (incidence 1:4508) were detected. Nine of them were homozygotes (D444H/D444H), and 4 compound heterozygotes carrying D444H combined with Q456H, T532M, C186Y and R157H, respectively. All were asymptomatic and supplemented with 10mg biotin. Although the number of screened neonates is rather small, it may be suggested that the incidence of the partial BTD infants is the highest ever reported. Detection of BTD should be added to the Greek national neonatal screening program.

Maternal chronic hepatitis B virus does not affect neonatal biotinidase activity

BACKGROUND

Biotinidase activity is closely related to liver function.

AIM

To evaluate whether maternal chronic hepatitis B virus (HBV) infection affects neonatal biotinidase activity.

PATIENTS AND METHODS

Twenty-three asymptomatic pregnant women with HBV (group A) and 28 healthy pregnant women (controls) in the delivery room and their newborns (cord blood) underwent laboratory examinations. Serological HBV and liver function tests were performed with standard techniques, while biotinidase activity was measured with an HPLC method.

RESULTS

Serological HBV tests and HBV DNA showed chronic HBV (precore mutant G1896A) in group A, whereas anti-HBc and anti-HBe were detected in their neonates. Liver function chemistry was found normal in controls and both groups of newborns. Moderately increased transaminases were found in the infected mothers. Interestingly, albumin levels did not differ among the studied groups. Biotinidase activity in HBV mothers (5.76+/-0.6 nmol/min/mL) was significantly decreased (p<0.001) as compared to controls (8.43+/-0.65 nmol/min/mL). The enzyme activity did not differ among the neonates. Biotinidase activity inversely correlated with transaminases but not with albumin or with HBV-DNA levels.

CONCLUSIONS

Decreased biotinidase activities were evaluated in mothers with HBV and normal in their neonates. Biotin supplementation in the diseased mothers may prevent possible symptoms due to biotin recycling impairment.

Serum and liver tissue biotinidase enzyme activity in rats which were administrated to valproic acid

Valproic acid (VPA) is an antiepileptic drug widely used and well-tolerated by most of patients. Its non-dose-dependent side effects seen mostly are the temporary gastrointestinal disturbances including anorexia and nausea, and hepatoxicity. As to its dose-dependent side effects are the weight loss, tremor, skin eruption and the alopecia. In this study we aimed to put forward the biotinidase deficiency considered as a possible cause of alopecia in the rats administered with valproic acid, and the correlation between liver and serum biotinidase enzyme activities (BEA) and transaminases, albumin and serum valproic acid levels. In our study, 4 groups of which one of them was a control group, each consisting of 15 male Wistar rats was organized. 200, 400, and 600 mg/kg/day of VPA, and distilled water, two divided doses per day, were administered per orally to VPA-1, VPA-2, VPA-3, and control group, respectively, in 60 days. Their serum and liver biotinidase enzyme activities, serum AST, ALT, albumin, and valproic acid levels were measured. Alopecia was seen in the subjects of 6.6% of VPA-1, 13.3% of VPA-2, and 26.6% of VPA-3. Significant difference in the liver tissues BEA was noted only between VPA-3 and the control group. Reductions were observed both in the liver tissues BEA and the serum BEA levels, which are inversely proportional to the VPA doses. A positive correlation between the liver biotinidase enzyme activities and the serum valproic acid levels, and the negative correlation between the liver tissues biotinidase activities and the serum valproic acid levels were noted, respectively. As a conclusion, the partial alopecia which is an initial symptom of reduced biotinidase activity may also be created depending on the reduction of biotinidase activity during valproic acid therapy. The alopecia which may further be observed in the patients receiving valproic acid therapy may be prevented by means of administration of biotin in a dose of 10 mg/day.

Cutaneous manifestations of nutritional deficiency

PURPOSE OF REVIEW

Nutritional deficiency, a global problem, remains uncommon in developed nations. Associated morbidity and mortality make it imperative that clinicians remain familiar with the clinical signs and symptoms of nutritional deficiencies to facilitate diagnosis. This article will review the cutaneous findings and recent literature regarding B12, niacin, zinc, vitamin A, kwashiorkor, biotin and selenium deficiencies, along with the clinical entities of noma and phrynoderma.

RECENT FINDINGS

Much of our understanding of the clinical manifestations of nutritional deficiencies comes from old literature; however, recent case reports and series have highlighted several patient populations that may be at risk from acquired deficiencies, including patients with anorexia nervosa, cystic fibrosis, patients receiving long-term tube-feeding and those with perceived or real food allergy. There can be significant clinical overlap between various micronutrient, protein and vitamin deficiencies. Additionally, providers should consider the possibility of multiple deficiencies coexisting in individual patients.

SUMMARY

Reports of nutritional deficiency continue to surface in developed nations and pediatricians need to have a basic understanding of their clinical manifestations. The skin is commonly affected and can be the presenting sign of illness. A higher clinical suspicion needs to be maintained in certain populations.