A pilot longitudinal study of the use of waxy maize heat modified starch in the treatment of adults with glycogen storage disease type I: a randomized double-blind cross-over study.

BACKGROUND: Uncooked corn-starch (UCCS) has been the mainstay of therapy for the hepatic glycogen storage diseases (GSD) but is not always effective. A new starch (WMHMS) has demonstrated a more favourable short-term metabolic profile. OBJECTIVE: To determine efficacy and safety of a new uncooked starch (WMHMS) compared to UCCS over 16 weeks treatment with each. METHOD: A double-blind cross-over study of 10 adults (aged 16 - 38 years, six male) with GSD Ia and Ib. After an individualised fast, subjects were randomised to take a 50 g starch-load of either WMHMS or UCCS. Starch-loads terminated when blood glucose was < 3.0 mmol/L or the subject felt subjectively hypoglycaemic. Anonymous biochemical profiles were assessed by 2 investigators and a starch administration schedule recommended. Each starch was delivered in coded sachets and intake was monitored for the following 16 weeks. After a washout period, the protocol was repeated with the alternative product. RESULTS: 4 subjects failed to establish therapy on the cross-over limb. Data from 7 paired starch load showed: longer median fasting duration with WMHMS (7.5 versus 5 hours; p = 0.023), slower decrease in the glucose curve (0.357 versus 0.632 mmol/hr p = 0.028) and less area under insulin curves for the first 4 hours (p = 0.03). Two of six subjects took 50% or less WMHMS compared to UCCS and one took more. Plasma triglycerides, cholesterol and uric acid were unchanged after each study phase. CONCLUSION: WMHMS leads to significant reduction in insulin release and reduced starch use in some GSD patients.

Adults with untreated phenylketonuria: out of sight, out of mind.

Some people with phenylketonuria who were born before screening began were never treated and are still alive. Here we report that far fewer people with untreated phenylketonuria were detected than are thought to exist (about 2000). The majority of those traced had high support needs, challenging behaviour and other symptoms of phenylketonuria. No significant differences were found between those who had or had not tried the phenylalanine-restricted diet. A randomised controlled trial is required to examine the effect of trying the low-phenylalanine diet for people with untreated phenylketonuria.

Factors influencing outcomes in the offspring of mothers with phenylketonuria during pregnancy: the importance of variation in maternal blood phenylalanine.

BACKGROUND: Developmental delay in the offspring of women with phenylketonuria (PKU) can be prevented by maintaining maternal blood phenylalanine (Phe) within a target range (100-250 micromol/L). OBJECTIVE: We aimed to analyze outcomes in the offspring of women with PKU during pregnancy and to identify prognostic factors. DESIGN: Occipitofrontal circumference at birth (OFC-B); developmental scores [developmental quotient (DQ) and intelligence quotient (IQ)]at 1, 4, 8, and 14 y; and the time of starting a Phe-restricted diet (before or after conception) were collected. The influence of maternal Phe concentrations during pregnancy on offspring outcomes also was assessed. RESULTS: The study included 105 children born to 67 mothers with PKU. Mean (+/-SD) OFC-B z scores did not differ between the preconception and postconception diet groups (0.42 +/- 1.24 and -0.96 +/- 1.19, respectively). DQ at 1 y and IQ at 8 y were higher in offspring from the preconception diet group than in offspring from the postconception diet group [DQ: 107 +/- 13.8 and 99.3 +/- 13.3, respectively (P = 0.014); IQ: 110.6 +/- 14.8 and 91.2 +/- 23.9, respectively (P = 0.005)]. Maternal Phe concentrations correlated negatively with DQ and IQ scores, and variations (SD) in all maternal blood Phe correlated negatively with 4-, 8-, and 14-y IQ scores (r = -0.385, -0.433, and -0.712; P = 0.002, 0.008, and 0.031, respectively), even when concentrations were consistently within the target range. CONCLUSIONS: The study suggests that women with PKU should start a Phe-restricted diet before conception. Maintenance of maternal blood Phe within the target range predicts good offspring outcomes, but variations even within that range should be avoided.

The longest-surviving patient with classical maple syrup urine disease.

The clinical problems, dietary management and biochemical monitoring over a 40-year period of the longest-surviving patient with maple syrup urine disease are described. Her case illustrates that a good outcome can be obtained with early diagnosis and institution of a diet restricted in branched-chain amino acids. Changes in dietary supplementation have benefited her in terms of nutrition and quality of life. Consistently high blood concentrations of branched-chain amino acids have not been associated with neuropsychometric decline.

Maternal phenylketonuria: experiences from the United Kingdom.

Charles Dent was one of the first physicians to recognize the teratogenic effects of maternal phenylalanine (Phe) on the fetus in 1956. This article describes the clinical experiences of women with phenylketonuria (PKU) within the unit that was established by Dent in the United Kingdom. Between 1977 and 2002, 79 infants were born to women with PKU. Of the 79, 18 (23%) were conceived while the women were on a normal diet with high blood Phe levels. The mean birth weight was 2.89 kg, and head circumference was 32.8 cm. At 1 year, the mean developmental quotient was 105.5 and at 4 years was 82.3. Four of these infants had congenital heart disease (2 of whom died as a result). In the remaining 61 infants, Phe-restricted diet started before conception. None of them had congenital heart disease. The mean birth weight was 3.23 kg, and head circumference was 34.0 cm. At 1 year, mean developmental quotient was 108.0 and at 4 years was 90.9. They continue to be followed up with additional neuropsychometric assessments at 8 and 14 years of age. This cohort is a proportion of infants who were born to mothers with PKU in the United Kingdom. Between 1978 and 1997, 255 live births were reported. Of these, 56% were conceived on unrestricted diet with subsequently poor outcome. This relatively high rate of conception off PKU diet is likely to reflect the scarcity of medical services for adults with metabolic disorders. We conclude that many features of the maternal PKU syndrome can be prevented but still occur because of the lack of appropriate resources to care for at-risk women. The precise targets for blood Phe and other nutrients during pregnancy are not entirely clear, neither are the reasons that some offspring are spared the harmful effects of Phe. The impact of the postnatal environment in which these infants find themselves requires additional assessment, too.