Breastfeeding infants with phenylketonuria in the United States and Canada

Human milk and breastfeeding during ketogenic diet therapy in infants with epilepsy: Clinical practice guideline

Ketogenic diet therapy (KDT) is a safe and effective treatment for epilepsy and glucose transporter type 1 (GLUT1) deficiency syndrome in infancy. Complete weaning from breastfeeding is not required to implement KDT; however, breastfeeding remains uncommon. Barriers include feasibility concerns and lack of referrals to expert centres. Therefore, practical strategies are needed to help mothers and professionals overcome these barriers and facilitate the inclusion of breastfeeding and human milk during KDT. A multidisciplinary expert panel met online to address clinical concerns, systematically reviewed the literature, and conducted two international surveys to develop an expert consensus of practical recommendations for including human milk and breastfeeding in KDT. The need to educate about the nutritional benefits of human milk and to increase breastfeeding rates is emphasized. Prospective real-world registries could help to collect data on the implementation of breastfeeding and the use of human milk in KDT, while systematically including non-seizure-related outcomes, such as quality of life, and social and emotional well-being, which could improve outcomes for infants and mothers.

Breast feeding in infants diagnosed with phenylketonuria (PKU): a scoping review

BACKGROUND

Phenylketonuria (PKU) is the most common inherited disease of amino acid metabolism, characterised by elevated levels of phenylalanine (Phe). There is a lack of infant feeding guidance for those with PKU. From birth to 6 months of age, breast feeding is the optimal nutrition for an infant and continuing breast feeding for infants with PKU is recommended by European guidelines. However, human breast milk contains Phe in varying quantities, and therefore, the effects breast feeding might have on infants with PKU needs careful consideration.

AIM

To assess the effects of breast feeding (exclusive or partial) compared with low-Phe formula feeding in infants diagnosed with PKU, on blood Phe levels, growth and neurodevelopmental scores.

METHODS

The Cochrane Inborn Errors of Metabolism Trials Register, MEDLINE and Embase were searched (date of latest search: 9 August 2022). Studies were included if they looked at the effects of breast feeding in infants diagnosed with PKU compared with formula feeding. Predetermined outcomes included blood Phe levels, growth in the first 2 years of life and neurodevelopmental scores.

RESULTS

Seven observational studies (282 participants) met the inclusion criteria. All studies compared continuation of breast feeding with low-Phe formula versus formula feeding only. While most studies concluded that there was no difference in mean serum Phe levels in their follow-up period, two reported that breastfed infants were more likely to have a normal mean Phe level. Two studies described no difference in mean weight gain after birth, while one found that breastfed infants were more likely to have higher mean weight gain. Two studies commented that breastfed infants achieved higher developmental scores in childhood as compared with formula fed infants.

CONCLUSION

Although there are no randomised trials, observational evidence suggests that continuation of breast feeding and supplementation with low-Phe formula is safe and may be beneficial for infants diagnosed with PKU.

Feeding difficulties in patients with Phenylketonuria

PURPOSE

to analyze the results of an instrument that aims to assist in the identification of feeding difficulties in children with Phenylketonuria (PKU), compared to children without the disease.

METHODS

cross-sectional, controlled study with a convenience sample composed of patients with PKU and healthy individuals, matched for age and sex. The invitation to participate in the study was made through the dissemination of the research on social networks. The answers were provided by the guardians, 46 controls and 28 patients agreed to participate. In addition to these, 13 guardians of patients being followed up at an Outpatient Clinic for the Treatment of Inborn Errors of Metabolism were invited by phone call, and 12 accepted the invitation. All participants answered the Brazilian Infant Feeding Scale (in Portuguese Escala Brasileira de Alimentação Infantil (EBAI)) electronically.

RESULTS

the study included 86 participants, 40 patients (median of age = 2 years; interquartile range (IQR) = 2 - 4) and 46 controls (median of age = 3.5 years; IQR = 2 - 5.25). Ten (25%) patients and 13 (28.3%) controls had suspicion of feeding difficulties, demonstrating a similar frequency of feeding difficulties between groups. The study found that PKU patients had less feed autonomy (p = 0.005), were less breastfed (p = 0.002) and used more baby's bottle than controls (p = 0.028).

CONCLUSION

the frequency of feeding difficulties reported by caregivers was similar between the comparison groups, but children with PKU had less feed autonomy, were less breastfed and used more baby's bottles when compared to children without the disease.

Phenylalanine hydroxylase deficiency treatment and management: A systematic evidence review of the American College of Medical Genetics and Genomics (ACMG)

PURPOSE

Elevated serum phenylalanine (Phe) levels due to biallelic pathogenic variants in phenylalanine hydroxylase (PAH) may cause neurodevelopmental disorders or birth defects from maternal phenylketonuria. New Phe reduction treatments have been approved in the last decade, but uncertainty on the optimal lifespan goal Phe levels for patients with PAH deficiency remains.

METHODS

We searched Medline and Embase for evidence of treatment concerning PAH deficiency up to September 28, 2021. Risk of bias was evaluated based on study design. Random-effects meta-analyses were performed to compare IQ, gestational outcomes, and offspring outcomes based on Phe ≤ 360 μmol/L vs > 360 μmol/L and reported as odds ratio and 95% CI. Remaining results were narratively synthesized.

RESULTS

A total of 350 studies were included. Risk of bias was moderate. Lower Phe was consistently associated with better outcomes. Achieving Phe ≤ 360 μmol/L before conception substantially lowered the risk of negative effect to offspring in pregnant individuals (odds ratio = 0.07, 95% CI = 0.04-0.14; P < .0001). Adverse events due to pharmacologic treatment were common, but medication reduced Phe levels, enabling dietary liberalization.

CONCLUSIONS

Reduction of Phe levels to ≤360 μmol/L through diet or medication represents effective interventions to treat PAH deficiency.

Breastfeeding and Inborn Errors of Amino Acid and Protein Metabolism: A Spreadsheet to Calculate Optimal Intake of Human Milk and Disease-Specific Formulas

Human milk (HM) offers important nutritional benefits. However, except for phenylketonuria (PKU), there are little data on optimal levels of consumption of HM and a special formula free of disease-related amino acids (SF-AA) in infants with inborn errors of metabolism of amino acids and proteins (IEM-AA-P). We designed a spreadsheet to calculate the amounts of SF-AA and HM required to cover amino acid, protein, and energy needs in patients with the nine main IEM-AA-P in infants aged under 6 months. Upon entering the infant's weight and the essential amino acid or intact protein requirements for the specific IEM, the spreadsheet calculates the corresponding required volume of HM based on the amino acid concentration in HM. Next, the theoretical daily fluid intake (typical range, 120-200 mL/kg/day) is entered, and the estimated daily fluid intake is calculated. The required daily volume of SF-AA is calculated as the difference between the total fluid intake value and the calculated volume of HM. The spreadsheet allows for the introduction of a range of requirements based on the patient's metabolic status, and includes the option to calculate the required volume of expressed HM, which may be necessary in certain conditions such as MMA/PA and UCD. In cases in which breastfeeding on demand is feasible, the spreadsheet determines the daily amount of SF-AA divided over 6-8 feeds, assuming that SF-AA is administered first, followed by HM as needed. Intake data calculated by the spreadsheet should be evaluated in conjunction with data from clinical and nutritional analyses, which provide a comprehensive understanding of the patient's nutritional status and help guide individualized dietary management for the specific IEM.

A Retrospective Chart Review and Infant Feeding Survey in the Irish Phenylketonuria (PKU) Population (2016-2020)

Phenylketonuria (PKU) is an inherited disorder of protein metabolism. It is generally treated using dietary management with limited intake of phenylalanine (Phe). Partial breastfeeding (BF) is encouraged among mothers of infants with PKU, together with a Phe-free mixture of synthetic amino acids. Our aim was to describe our current BF rates and complementary feeding practices, as well as examining parental experiences of infant feeding. The objective was to better understand the challenges faced by families so that improvements can be made to clinical care. A chart review was carried out on 39 PKU patients, examining the BF rate and duration, use of second stage synthetic protein (SP), and average complementary feeding age. A parental questionnaire on complementary feeding and BF experience was designed: 26% of babies were partially breastfed at three months of age; 70% of mums would like to have breastfed for longer and cited PKU as a reason for stopping; 52% of parents reported challenges during the complementary feeding process including food refusal, protein calculation, and anxiety around maintaining good Phe levels. Suggestions to improve BF continuation and duration include active promotion of the benefits and suitability, access to lactation consultant, and peer support. The delay in introducing a second stage SP may contribute to long-term bottle use for SP. Improved patient education, written resources, and support is necessary to improve food choices and long-term acceptance of SP.

Breastfeeding practices for infants with inherited metabolic disorders: A survey of registered dietitians in the United States and Canada

Background

Objective

Design

Results

Conclusions

Variants of the phenylalanine hydroxylase gene in neonates with phenylketonuria in Hainan, China

OBJECTIVE

To investigate the incidence of phenylalanine hydroxylase (PAH) deficiency and PAH genotypes in neonates in Hainan, China. Methods: We performed heal stick to collect blood and obtain dry blood spot specimens from newborns in Hainan from January 2007 to December 2016. Phenylalanine (Phe) concentration in these dry blood spots was measured by the fluorescence method to screen phenylketonuria (PKU). For suspicious samples, the genotypes of the PAH gene were amplified by biotin labeled oligonucleotide primers. Polymerase chain reaction (PCR) products were then analyzed by flow-through hybridization to detect genotypes. At the same time, peripheral blood samples of children suspicious of PKU and their parents were used to perform gene sequencing. Results: Of the 914,520 newborns screened, 29 of them had PAH deficiency. The incidence of PAH deficiency in Hainan was 3.17/100,000. A total of 58 mutant alleles belonging to 15 different types were identified in the 29 patients. In terms of genotypes frequency, the top 4 were: c.611A > G 20.7% (12/58) , c.728G > A 17.2%, c.158G > A 15.2% (9/58) and c.721C > T 13.8% (8/58). The frequencies of other genotypes were all below 10%. Conclusion: The incidence of PAH deficiency in Hainan is relatively high among all provinces in southern China. With a total frequency of 67.2%, c.611A > G, c.728G > A, c.158G > A and c.721C > T, and are the most common PAH gene genotypes.

Early life nutrition

Nutritionally, the first 1,000 days of an infant's life - from conception to two years - has been identified as a highly influential period, during which lasting health can be achieved. Significant evidence links patterns of infant feeding to both short and long-term health outcomes, many of which can be prevented through nutritional modifications. Recommended globally, breastfeeding is recognised as the gold standard of infant nutrition; providing key nutrients to achieve optimal health, growth and development, and conferring immunologic protective effects against disease. Nevertheless, infant formulas are often the sole source of nutrition for many infants during the first stage of life. Producers of infant formula strive to supply high quality, healthy, safe alternatives to breast milk with a comparable balance of nutrients to human milk imitating its composition and functional performance measures. The concept of 'nutritional programming', and the theory that exposure to specific conditions, can predispose an individual's health status in later life has become an accepted dictum, and has sparked important nutritional research prospects. This review explores the impact of early life nutrition, specifically, how different feeding methods affect health outcomes.

Early feeding practices in infants with phenylketonuria across Europe

Background

In infants with phenylketonuria (PKU), dietary management is based on lowering and titrating phenylalanine (Phe) intake from breast milk or standard infant formula in combination with a Phe-free infant formula in order to maintain blood Phe levels within target range. Professionals use different methods to feed infants with PKU and our survey aimed to document practices across Europe.

Methods

We sent a cross sectional, survey monkey® questionnaire to European health professionals working in IMD. It contained 31 open and multiple-choice questions. The results were analysed according to different geographical regions.

Results

Ninety-five centres from 21 countries responded. Over 60% of centres commenced diet in infants by age 10 days, with 58% of centres implementing newborn screening by day 3 post birth. At diagnosis, infant hospital admission occurred in 61% of metabolic centres, mainly in Eastern, Western and Southern Europe. Breastfeeding fell sharply following diagnosis with only 30% of women still breast feeding at 6 months.

53% of centres gave pre-measured Phe-free infant formula before each breast feed and 23% alternated breast feeds with Phe-free infant formula. With standard infant formula feeds, measured amounts were followed by Phe-free infant formula to satiety in 37% of centres (n = 35/95), whereas 44% (n = 42/95) advised mixing both formulas together. Weaning commenced between 17 and 26 weeks in 85% centres, ≥26 weeks in 12% and < 17 weeks in 3%.

Discussion

This is the largest European survey completed on PKU infant feeding practices. It is evident that practices varied widely across Europe, and the practicalities of infant feeding in PKU received little focus in the PKU European Guidelines (2017). There are few reports comparing different feeding techniques with blood Phe control, Phe fluctuations and growth. Controlled prospective studies are necessary to assess how different infant feeding practices may influence longer term feeding development.

The Effects of Breastfeeding in Infants With Phenylketonuria

PURPOSE

In the early years of phenylketonuria (PKU) treatment, mothers and healthcare professionals often decide to discontinue breastfeeding after the diagnosis of PKU in infants. It was believed to be the only effective way to monitor the infant's intake and allow for precise titration and measurement of the intake of phenylalanine (Phe). In the early 1980s, with the determination of low concentration of Phe in breast milk, breast milk supplemented with Phe-free formula has become an acceptable dietary treatment for infants with PKU. Today, breastfeeding is encouraged and well established in PKU patients. The aim of the present study is to investigate the prevalence and duration of breastfeeding, the effect of breastfeeding on serum Phe levels, and weight gain in infants with PKU.

DESIGN AND METHODS

Data were collected from chart reviews. Medical records of 142 children with PKU diagnosed via the national neonatal screening program were analyzed retrospectively.

RESULTS

Of the 41 infants with complete medical records, 40 (97.6%) were breastfed following delivery whereas only one (2.4%) was bottle fed. After the diagnosis, breastfeeding was continued in 25 (61%) infants with phenylalanine-free amino acid based protein substitute. The mean duration of breastfeeding was 7.4±4.0 (1-15) months. Serum Phe concentration of breastfed infants (280±163 μmol/L) was significantly lower than non-breastfed infants (490±199 μmol/L) (p<0.001). Mean monthly weight gain in the first year of life was significantly higher in breastfed patients (493±159 g/month) compared to non-breastfed patients (399±116 g/month) (p=0.046).

CONCLUSION

In the first year of life, weight gain and serum Phe levels were more favorable in breastfed infants with PKU compared to non-breastfed infants with PKU.

Breast milk feeding in infants with inherited metabolic disorders other than phenylketonuria - a 10-year single-center experience

BACKGROUND

Published data on breast milk feeding in infants suffering from inherited metabolic disorders (IMDs) other than phenylketonuria (PKU) are limited and described outcome is variable.

OBJECTIVE

We aimed to evaluate retrospectively whether breastfeeding and/or breast milk feeding are feasible in infants with IMDs including organic acidemias, fatty acid oxidation disorders, urea cycle disorders, aminoacidopathies or disorders of galactose metabolism.

METHODS

Data on breastfeeding and breast milk feeding as well as monitoring and neurological outcome were collected retrospectively from our database of patients with the mentioned IMD, who were followed in our metabolic center within the last 10 years.

RESULTS

Twenty patients were included in the study, who were either breast fed on demand or received expressed breast milk. All the infants were evaluated clinically and biochemically at 2-4-week intervals, with weight gain as the leading parameter to determine metabolic control. Good metabolic control and adequate neurological development were achieved in all patients but one, who experienced the only metabolic crisis observed within the study period.

CONCLUSION

Breast milk feeding with close clinical and biochemical monitoring is feasible in most IMD and should be considered as it offers nutritional and immunological benefits.

Challenges to breastfeeding infants with phenylketonuria

Breastfeeding duration for infants with phenylketonuria (PKU) is less than other full-term infants. However, no study has examined the challenges encountered by mothers' breastfeeding infants with PKU. In 75 mothers of a child with PKU, three categories of breastfeeding challenges were identified: common breastfeeding issues, breastfeeding and PKU, and no challenges. The common breastfeeding issues can be identified in the literature but for these mothers, the issues are heightened due to frequent phenylalanine (Phe) monitoring. Even so, many mothers adapt breastfeeding to maintain desired Phe levels. A few mothers had no issues and were the exception, not the norm.