Newborn screening for galactosemia: a new method used in Manitoba.

In July 1983, the Manitoba Perinatal Screening Programme modified its existing procedure for neonatal screening for galactosemia by introducing quantitation of total galactose plus galactose-1-phosphate from dried blood spots using the Multistat centrifugal analyzer. The first 4 years of experience with this method in combination with the Beutler spot test for galactose-1-phosphate uridyl transferase activity is the subject of this report. Of 70,336 newborns screened, 142 (0.20%) met the criteria for clinical follow up. Of these, one child was confirmed to have classical galactosemia and nine children were found to be Duarte/galactosemia genetic compounds. This method of galactosemia screening has proven to be rapid, sensitive, efficient, and the method of choice for mass screening of disorders of galactose metabolism.

Symptomatic and asymptomatic methylenetetrahydrofolate reductase deficiency in two adult brothers.

We describe two brothers with 5,10-methylene tetrahydrofolate reductase (MTHFR) deficiency. The younger patient first developed limb weakness, incoordination, paresthesiae, and memory lapses at age 15 years, and by his early twenties he was wheelchair bound. His older brother remains asymptomatic at age 37 years. Both had homocystinuria and homocystinemia and low plasma levels of methionine. MTHFR activities in cultured skin fibroblasts of both patients were < 10% control and residual enzyme activities were markedly reduced on heating. The parents had intermediate enzyme activities and the reductase in the father (who had unexplained paraparesis and homocystinemia), but not in the mother, was also thermolabile. Both patients were treated with oral folate and betaine which improved, but did not totally correct, their biochemical abnormality. MTHFR deficiency should be considered in the differential diagnosis of unexplained neurologic disease in adolescents and adults.

Vitamin D deficiency in a Manitoba community.

OBJECTIVE: Using a cross-sectional survey, to investigate the vitamin D status of a random sample of 80 mother-child pairs (child age 3-24 months) in a Manitoba community with a high incidence of rickets. METHOD: A questionnaire on feeding habits, gestational history, maternal diet and vitamin supplements was administered to mothers in their homes with the assistance of a local interpreter. Venous blood was collected from both mother and child for serum 25-hydroxyvitamin D levels. RESULTS: Of 91% babies initially breastfed, 36% received no formula or milk after weaning and 40% received no vitamin supplements. 24% of mothers took no vitamin supplements during pregnancy and lactation. Knowledge about rickets was poor. In 43% of children and 76% of mothers, serum 25-hydroxyvitamin D levels were below normal range. CONCLUSIONS: Vitamin D levels are low in this population due to lack of fortified dairy products and vitamin D supplements. A public health program should include counseling on rickets and vitamin D supplementation for all infants and pregnant or lactating women.

PIP: In the isolated Island Lake area of northern Manitoba, which has a high incidence of rickets, interviews were conducted with 80 mothers, each with a child at least 2 years old, living in St. Theresa Point and Garden Hill in their homes during June-July 1987 to determine their knowledge and attitudes towards rickets. Nurses obtained blood samples from the women and their young children so the researchers could determine the vitamin D status of both. The mother-child pairs were native Canadians from the Ojibway linguistic group that speaks its own dialect of Ojibway-Cree. Mothers initially breast fed 91% of the children. After weaning, 1/3 of infants received neither infant formula nor milk. No vitamin supplements were given to 40%. Many of the children who did receive vitamin supplements did not receive them regularly. 70% of the mothers did not drink any milk. 24% were milk-intolerant. 24% took no vitamin supplements during pregnancy and lactation. Mothers who did take supplements did not do so regularly. 17% claimed that their skin was sensitive to sunlight. 84% of mothers in one community had never heard of rickets. Most did not know its cause. Neither mothers nor the children were exposed to the sunlight in the summer. When outside, almost all small infants were completely covered to protect them from the elements. The mean 25-hydroxy-vitamin D level was 26.2 nmol/l for the children and 19.8 nmol/l for the mothers. 43% of children and 76% of mothers had a 25-hydroxy-vitamin D level below the normal range. These high levels of vitamin D insufficiency were even more troublesome given that the blood was taken in late June and July when vitamin D levels would be likely to be at their highest. The dearth of vitamin D fortified dairy products and vitamin supplements greatly contributed to the low level of vitamin D status in this area. The findings show a need for public health officials to include education on rickets and vitamin D supplementation for all infants and pregnant or lactating women.

Vitamin-D-deficient rickets in Manitoba, 1972-84.

Vitamin-D-deficient rickets still exists in children in Manitoba and adjacent areas. Between 1972 and 1984, 48 cases were documented at Winnipeg Children's Hospital. The patients ranged in age from 1 to 49 months; 40 were Canadian natives (38 Indians and 2 Inuit), most of whom lived in the Island Lake area of northern Manitoba. Of the 48, 16 had clinical signs of rickets, 12 had tetany due to hypocalcemia and 38 had radiologic evidence of rickets. Hypocalcemia was found in 27, and hypophosphatemia in 19; hyperaminoaciduria was found in 7 of 20. All 48 had elevated serum alkaline phosphatase levels. In addition to rickets, 16 patients aged 12 months or more had evidence of malnutrition. Climate and lifestyle in northern areas of the Canadian midwest result in little or no biosynthesis of vitamin D by solar radiation; therefore, adequate dietary vitamin D intake is essential to prevent deficiency. The diets of pregnant women and infants in these areas are deficient in vitamin D. The authors recommend vitamin D supplements for all pregnant women and infants in areas of risk to eradicate this preventable disease.

Relationships between maternal glucose intolerance and neonatal blood glucose.

Blood glucose changes in 63 infants during the first three hours of life were related to indices of glucose tolerance of their mothers. Of the mothers, 34 had insulin-dependent diabetes, 16 had gestational diabetes, and 11 had minor abnormalities of glucose tolerance. The fasting blood glucose level of the mother and the umbilical cord blood glucose level were both proportional to the rate of glucose decline in the infant after birth which, in turn, was inversely related to the lowest glucose level attained within three hours. Hypoglycemia occurred in 77% of the infants of diabetic mothers, 25% of the infants of mothers with gestational diabetes, and one of 12 (8%) of infants of mothers with minor degrees of glucose intolerance. The blood glucose level at two hours during an oral glucose tolerance test in the mother can be used to predict the probability of her infant having neonatal hypoglycemia.

Effect of abnormal glucose tolerance in pregnancy on infant mortality rate and morbidity. A prospective study.

Ninety-five pregnant women, not previously known to have diabetes but suspected of being at risk for the disease because of obesity, glycosuria, family history, or obstetric history, underwent oral and intravenous glucose tolerance tests in the last trimester of pregnancy. Several methods were used to categorize the degree of abnormality, but none was of value in predicting pregnancy outcome. Perinatal mortality and malformation rates in the offspring of these women were no greater than those of the over-all infant population at this Center and were much lower than those in infants born to women with overt diabetes. Causes of infant morbidity were not increased, with the exception of overweight babies, hypoglycemia, and hypocalcemia. Umbilical vein glucose level correlated significantly with the mothers' blood glucose at the time of delivery. Cord insulin level correlated with infant birth weight and with University Group Diabetes Program number. Birth weight correlated with the degree of the mothers' obesity. It was concluded the documentation of the degree of glucose intolerance in the mother is of little value in predicting fetal outcome but may indicate infants at risk for hypoglycemia and hypocalcemia.

Increased prevalence of hereditary metabolic diseases among native Indians in Manitoba and northwestern Ontario.

OBJECTIVE: To compare the prevalence of hereditary metabolic diseases in the native and non-native populations of Manitoba and northwestern Ontario. DESIGN: Retrospective analysis. SETTING: Children's Hospital, Winnipeg. PATIENTS: Patients were selected by three methods: laboratory tests designed to screen patients suspected of having a metabolic disease, laboratory investigation of newborn infants with abnormalities detected through screening, and investigation of near relatives of probands with disease. RESULTS: A total of 138 patients with organic acid, amino acid and carbohydrate disorders were seen from 1960 to 1990. Of these, 49 (36%) were native Indians (Algonkian linguistic group). This was in sharp contrast to the proportion of native Indians in the total study population (5.8%). Congenital lactic acidosis due to pyruvate carboxylase deficiency (13 patients), glutaric aciduria type I (14 patients) and primary hyperoxaluria type II (8 patients) were the most common disorders detected. Other rare disorders included glutaric aciduria type II (one patient), 2-hydroxyglutaric aciduria (one patient) and sarcosinemia (one patient). Underreporting, especially of glutaric aciduria type I and hyperoxaluria type II, was likely in the native population. CONCLUSIONS: Hereditary metabolic diseases are greatly overrepresented in the native population of Manitoba and northwestern Ontario. We recommend that native children who present with illnesses involving disturbances of acid-base balance or with neurologic, renal or liver disease of unknown cause by investigated for a possible metabolic disorder.

Prognosis of infants of diabetic mothers in relation to neonatal hypoglycaemia.

A prospective follow-up study was conducted to determine whether neonatal hypoglycaemia in infants of diabetic mothers affects subsequent neurological and intellectual performance. 37 such infants (25 hypoglycaemic and 12 non-hypoglycaemic) were examined for physical, neurological and developmental performance at an average age of 4 1/2 years. 11 children were abnormal, with generalised retardation and neurological abnormalities, or delays in particular areas of development; three children were possibly abnormal; and 23 children were normal. Abnormality at follow-up could not be related to neonatal blood glucose level, to the duration of hypoglycaemia or to any other measurement made in the neonatal period, nor to any factor relating to the maternal diabetes. Compared with the normal children, the abnormal group had slightly small head-circumferences at birth relative to their gestational age, but a follow-up there was no difference in head size. At follow-up the children of diabetic mothers tended to be shorter than average. The poor prognosis of the infants in this study was not due to brain damage caused by neonatal hypoglycaemia.

Breast-feeding protects against infection in Indian infants.

A retrospective study was undertaken at two isolated Manitoba Indian communities to determine whether the type of infant feeding was related to infection during the first year of life. Of 158 infants 28 were fully breast-fed, 58 initially breast-fed and then changed to bottle-feeding and 72 fully bottle-fed. Fully bottle-fed infants were hospitalized with infectious diseases 10 times more often and spent 10 times more days in hospital during the first year of life than fully breast-fed infants. Diagnoses were mainly lower respiratory tract infection and gastroenteritis. Gastroenteritis occurred in only one breast-fed infant. Breast-feeding was strongly protective against severe infection requiring hospital admission and also against minor infection. The protective effect, which lasted even after breast-feeding was discontinued, was independent of family size, overcrowding in the home, family income and education of the parents. Measures to achieve breast-feeding for virtually all infants, particularly in northern communities, should be given high priority.

Fetal growth retardation in cigarette-smoking mothers is not due to decreased maternal food intake.

To determine whether the fetal growth-retarding effect of maternal cigarette smoking could be due to a lower dietary intake in smokers than in nonsmokers, the energy and nutrient intake of 302 smoking and 234 nonsmoking women were assessed toward the end of the last trimester of pregnancy. The women were from two socioeconomic groups which differed greatly in age, height, education, family income, racial origin, and pregnancy weight gain. Within each group, smokers had significantly smaller infants, but pregnancy weight gain was not different. Daily dietary intake of the smokers was not less than that of the nonsmokers; in fact, for some nutrients it was significantly greater. Therefore, fetal growth retardation due to smoking is not caused by the mother's diminished intake of food.

PIP: With informed consent, the energy and nutrient intake of 302 smoking and 234 nonsmoking women in their last trimester of pregnancy was assessed using 2 methods: 1) calculation of average daily nutrients intake from dietary history, and; 2) recall of all foods and drinks consumed during the previous 24 hours or during a typical day. The infants were measured after birth, and data were computerized and analyzed by standard statistical methods, including multiple regression analysis. The public and the private patients were from 2 socioeconomic groups which differed greatly in age; height; education; family income; racial origin; and pregnancy weight gain. The public patients were younger; had less education; had lower family income, and; 61% were native indians. The infants of smokers had significantly lower birth weights (216 grams less in the public group; 224 grams less in the private group); were shorter, and; in the private group alone, had smaller head circumferences. Gestational age did not differ in both groups. 1-minute Apgar scores were significantly higher in the infants of public smokers. It was concluded that fetal growth retardation in women who smoke during pregnancy is not attributed to a lower intake of food, compared to that of nonsmokers.

A simple screening test for fatty acid oxidation defects using whole-blood palmitate oxidation.

We report that measurement of whole-blood palmitate oxidation is a rapid and inexpensive screening test for fatty acid oxidation defects. The assay has been adapted from published assays using cultured fibroblasts or isolated white blood cells. Micro whole-blood samples are incubated with tritiated palmitic acid as substrate. The tritiated water produced is proportional to the mitochondrial beta-oxidation of palmitic acid. Patients with confirmed beta-oxidation defects show low whole-blood palmitate oxidation.

Relation of maternal cigarette smoking, obesity, and energy consumption to infant size.

The dietary energy intakes of 153 public patients (94 smokers and 59 nonsmokers) and 383 Private patients (208 smokers and 175 nonsmokers) were assessed in the last month of pregnancy. Birth weight and crown-heel length of offspring were related to maternal size (weight for height) and smoking habits. Birth weight and length increased significantly with increasing maternal weight for height in the Private group but not in the Public group. In both groups, and in all weight categories, infants of smokers were lighter and shorter than those of nonsmokers. Neither the fetal growth retardation in the smokers nor the fetal growth enhancement in the overweight mothers was explainable on the basis of maternal dietary energy intake. Maternal obesity and cigarette smoking act independently of each other and maternal overweight does not protect the fetus against the growth-retarding of smoking.

PIP: A study was conducted on 302 smoking and 234 nonsmoking mothers to assess the relationships among dietary intake, maternal smoking, and infant birth weight. The study involved 153 public patients (94 smokers, 59 nonsmokers) and 383 private patients (208 smokers, 175 nonsmokers). All results are graphed. In both the public and private groups, infant birth weights were significantly lower for smoking than for nonsmoking mothers. The sex distribution and gestational age of the infants did not differ between the 2 groups. Even in obese mothers, smoking had a fetal growth-retardation effect. Obesity does not, therefore, counteract the retarding effect of smoking. The growth retardation is not believed to be due to decreased nutritional intake but to a direct toxic effect of the smoking. Maternal obesity and maternal cigarette smoking are 2 variables which act independently of each other on the fetus.

An unusual aminoacidopathy associated with mitochondrial encephalomyopathy.

Five patients from two unrelated pedigrees are affected by an inherited form or forms of mitochondrial encephalomyopathy in which the exact site of the block in the respiratory chain has yet to be identified. All five patients regularly exhibit an unusual aminoacidopathy evident both in fasting plasma and in CSF. Alanine concentrations are elevated, reflecting high tissue pyruvate and lactate levels. Concentrations of the four essential amino acids threonine, methionine, tryptophan and lysine are substantially reduced, as are those of citrulline, ornithine and arginine. This pattern of amino-acid deficiency is apparently not due to failure to absorb the dibasic amino acids, to any abnormality of the urea cycle, to excessive synthesis and turnover of creatine, or to protein malnutrition. The aminoacidopathy presumably is a metabolic consequence of one or more impairments in the electron transport chain in mitochondria. A detailed explanation of its aetiology needs to be sought.

Carrier detection in glutaric aciduria type I using interleukin-2-dependent cultured lymphocytes.

Cultured interleukin 2 (IL-2)-dependent leukocytes from 13 patients with glutaric aciduria type I, 12 obligate carriers, 105 family members and 31 normal controls were assayed for glutaryl-CoA dehydrogenase activity. Of the 13 affected patients, 10 (all Ojibway Indian) had residual enzyme activity (2-13% of control) and 3 patients (all non-Indian) had undetectable enzyme activity. There was partial overlap between the distribution of enzyme activity in obligate heterozygotes and in normal controls (mean values +/- SD: 6.29 +/- 0.94 and 10.75 +/- 2.58 nmol/h per mg protein respectively). Using an arbitrary cutoff level of < 7 nmol/h per mg protein as presumptive evidence of carrier status, the observed frequency of carriers did not differ significantly from that expected from their a priori risk of carrier status. Thirteen per cent of the family members had inconclusive status (activity between 7 and 8.5 nmol/h per mg protein). The method appears suitable for carrier detection, although definitive carrier assignment awaits identification of the mutation(s) responsible for glutaric aciduria type I.

Protein-sensitive and fasting hypoglycemia in children with the hyperinsulinism/hyperammonemia syndrome.

OBJECTIVE: Because the hyperinsulinism/hyperammonemia (HI/HA) syndrome is associated with gain of function mutations in the leucine-stimulated insulin secretion pathway, we examined whether protein feeding or fasting was responsible for hypoglycemia in affected patients. STUDY DESIGN: Patients with HI/HA (8 children and 6 adults) were studied. All had dominantly expressed mutations of glutamate dehydrogenase and plasma concentrations of ammonium that were 2 to 5 times normal. The responses to a 24-hour fasting test were determined in 7 patients. Responses to a 1.5 gm/kg oral protein tolerance test in 12 patients were compared with responses of 5 control subjects. RESULTS: The median age at onset of hypoglycemia in the 14 patients was 9 months; diagnosis was delayed beyond age 2 years in 6 patients, and 4 were not given a diagnosis until adulthood. Fasting tests revealed unequivocal evidence of hyperinsulinism in only 1 of 7 patients. Three did not develop hypoglycemia until 12 to 24 hours of fasting; however, all 7 demonstrated inappropriate glycemic responses to glucagon that were characteristic of hyperinsulinism. In response to oral protein, all 12 patients with HI/HA showed a fall in blood glucose compared with none of 5 control subjects. Insulin responses to protein loading were similar in the patients with HI/HA and control subjects. CONCLUSION: The postprandial blood glucose response to a protein meal is more sensitive than prolonged fasting for detecting hypoglycemia in the HI/HA syndrome.

Atypical features of the hepatic form of carnitine palmitoyltransferase deficiency in a Hutterite family.

We describe hepatic carnitine palmitoyltransferase (CPT I) deficiency in three children (a brother and sister and their second cousin) from an extended inbred Hutterite kindred. The patients were first seen between 8 and 18 months of age with recurrent episodes of hypoketotic hypoglycemia accompanied by a decreased level of consciousness and hepatomegaly. One patient had two Reye syndrome-like episodes. Abnormal organic acids were rarely detected in urine. Serum total and free carnitine levels were elevated in all three patients. Fibroblast acyl-coenzyme A dehydrogenase activities were normal in all, but palmitic acid oxidation, performed in fibroblasts from one patient, was less than 10% of control values. Activity of CPT I in cultured skin fibroblasts from the three patients was 10% to 15% of control levels; CPT II activity was normal. Activity of CPT I and CPT II in muscle from one patient was normal. Atypical features in two of these patients were greatly elevated levels of liver enzymes and creatine kinase during acute episodes. The patients have recently been successfully treated with medium-chain triglycerides and avoidance of fasting. Early identification and treatment of this disorder may avert potentially fatal episodes of hypoglycemia.

Mitochondrial encephalomyopathy with associated aminoacidopathy in a male sibship.

We report two brothers with a previously undescribed type of mitochondrial encephalomyopathy and associated aminoacidopathy. Both have growth failure, progressive intellectual decline, deafness, neurologic dysfunction, exercise intolerance, lactic acidosis, and abnormal plasma and cerebrospinal fluid amino acid levels (elevated levels of alanine and low levels of threonine, methionine, citrulline, tryptophan, ornithine, arginine, and lysine). A muscle biopsy specimen taken from the younger, more severely affected brother showed abnormal mitochondrial morphology. Activities of the following enzymes in cultured fibroblasts from both boys were normal: pyruvate dehydrogenase, pyruvate carboxylase, phosphoenolpyruvate carboxykinase, cytochrome oxidase, reduced nicotinamide-adenine dinucleotide-cytochrome c reductase, and succinate cytochrome c reductase. Fibroblast mitochondria from the younger boy showed undetectable (less than 1% of control values) adenosine triphosphate synthesis with pyruvate and malate, whereas adenosine triphosphate synthesis with succinate was 70% of control values. These data indicate probably deficient activity of complex I of the electron transport chain. The boys' mother has progressive neurosensory hearing loss; their sister is clinically normal. Both mother and sister have many of the biochemical abnormalities found in the boys. It is possible, but not proved, that this disorder is inherited through maternal mitochondria.

Phenotypic variability in glutaric aciduria type I: Report of fourteen cases in five Canadian Indian kindreds.

We describe 14 patients with glutaric aciduria type 1 in five Canadian Indian kindreds living in Manitoba and northwest Ontario. The patients had marked clinical variability of the disease, even within families. Eight followed the typical clinical course of normal early growth and development until the onset of neurologic abnormalities, often precipitated by infection, between 6 weeks and 7 1/2 months of age. Five patients had early developmental delay; one was thought to be normal until 8 years of age. Three patients died, seven are severely mentally and physically handicapped, and four have only mild mental retardation or incoordination. Six patients had macrocephaly in the neonatal period. Computed tomography was done for 12 patients, and findings were abnormal in 11. Glutaric acid and 3-hydroxyglutaric acid were detected in increased amounts in the urine of all patients, but the concentrations were much lower than those in most other reported patients. Glutaryl coenzyme A dehydrogenase activity in skin fibroblasts, interleukin-2-dependent lymphocytes, or both, ranged from 0% to 13% of control values. There was no correlation between clinical severity and urine glutaric acid concentration or level of residual enzyme activity. We recommend that organic acid analysis of the urine be done in patients with unexplained cerebral palsy-like disorders, especially if the computed tomographic scan is abnormal. If there is suspicion of glutaric aciduria, glutaryl-coenzyme A dehydrogenase should be measured in fibroblasts or lymphocytes even if glutaric acid is not increased in the urine.