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Biomedical subjects

H L Levy

Publications and source records attributed to H L Levy.

At least 109 records · Page 6Linked to original sources
PubMed1990

Partial biotinidase deficiency: clinical and biochemical features.

Neonatal screening for profound biotinidase deficiency (less than 10% of the mean normal activity level) has identified a group of children with partial biotinidase deficiency (10% to 30% of mean normal activity). Because partial biotinidase deficiency may result in clinical consequences that may be prevented by treatment with biotin, we evaluated such individuals and their family members (1) to determine whether partial biotinidase deficiency is associated with symptoms and (2) to determine the inheritance pattern. We quantified serum biotinidase activity levels and obtained medical histories of probands, their parents and siblings, and additional family members. All children with partial deficiency were healthy at the time of diagnosis. One child, who was not initially treated with biotin, later developed hypotonia, hair loss, and skin rash, which resolved with biotin therapy. Four adults and three children with partial biotinidase deficiency were identified among family members of infants identified by neonatal screening. All these individuals were healthy, although one sibling had elevated urinary lactate excretion. A fifth adult with partial deficiency, found among clinically normal adult volunteers, later showed minor symptoms that resolved after biotin therapy. Like children with profound biotinidase deficiency, children with partial biotinidase deficiency are symptoms free at birth. However, the subsequent occurrence of symptoms of profound biotinidase deficiency in some persons with partial deficiency suggests that biotin therapy for this condition may be warranted.

Adult↗
PubMed1990

Phenylketonuria: MR imaging of the brain with clinical correlation.

Fifteen patients with biochemically documented phenylketonuria (PKU) were studied with use of magnetic resonance (MR) imaging with spin-echo T2-weighted pulse sequences. The resulting images demonstrated varying degrees of symmetric high signal intensity of the white matter within the posterior cerebral hemispheres. Involvement of the anterior hemispheres was seen only in cases with severe signal intensity changes. There was no involvement of the cerebral cortex, brain stem, or cerebellum. Moreover, no anatomic structural abnormalities were observed. Mild cortical atrophy was observed in eight of the 15 patients. There was no significant correlation between the patients' IQ scores and the level of MR signal intensity changes. Although MR imaging routinely shows relatively distinct abnormalities in patients with PKU, the clinical severity of the disease does not parallel its imaging severity.

Adolescent↗
PubMed1989

Nutritional therapy for selected inborn errors of metabolism.

Nutritional approaches are available for the management of several different classes of inborn metabolism errors. In phenylketonuria (PKU), phenylalanine is not properly metabolized; and its accumulation leads to neurologic dysfunction and metal retardation. Altering the diet to limit phenylalanine intake led to remarkable improvement in children with PKU. It was later found that instituting dietary therapy immediately after identification of the disorder in newborns prevented mental retardation. Throughout the 1960s nutritional therapies were found for other inborn disorders, including galactosemia, maple syrup urine disease, and homocystinuria. For the group of disorders associated with defects in the urea cycle, leading to profound hyperammonemia, therapy based on the concept of waste nitrogen excretion (i.e., by increasing excretion of urea cycle intermediates in the urine, nitrogen that would otherwise recycle as ammonia can be eliminated) dramatically produced better control of hyperammonemia and its consequences. Some inborn errors of metabolism respond to vitamin therapy. Biotin-related multiple carboxylase synthetase deficiency can be produced by either of two enzyme defects--holocarboxylase synthetase deficiency or biotinidase deficiency. Both are treatable with biotin supplementation. The symptoms of multiple carboxylase deficiency can also occur after intestinal resection or ingestion of raw eggs. Multiple carboxylase deficiency has been treated successfully in utero by giving the mother biotin supplements. Peroxisomal disorders may respond to dietary management. Liver disease in hereditary tyrosinemia may be accentuated by hypermethioninemia and treated by controlling the blood methionine level. Glycogen storage disease Type I, which causes hypoglycemia, can be controlled by oral administration of cornstarch.

Glycogen Storage Disease Type I↗
PubMed1989

Late onset of distinct neurologic syndromes in galactosemic siblings.

We discuss siblings with galactose-1-phosphate uridyl transferase deficiency who developed neurologic complications after the age of 30. One has partial complex seizures and the other has generalized seizures, progressive ataxia, and apraxia. As more galactosemic children survive into adulthood, more neurologic complications may become more prevalent.

Adult↗
PubMed1988

The New England Maternal PKU Project: identification of at-risk women.

Young women with phenylketonuria (PKU) are at risk for bearing children with mental retardation, microcephaly, heart defects, and low birthweight. These effects may be prevented if a low phenylalanine diet is maintained prior to and throughout pregnancy. This report describes the procedures of the New England Regional Maternal PKU Project for identifying and locating this population of at-risk women. Newborn screening records, routine umbilical cord blood screening, and PKU Clinic records provided most of the identifying information. We identified 235 women with hyperphenylalaninemia, ages 12 to 44 years. Of these, 183 had PKU or atypical PKU while 52 had non-PKU mild hyperphenylalaninemia. The 235 women represent 88 per cent of the expected number of women with hyperphenylalaninemia in New England. We identified more than the expected number of those with PKU but only 57 per cent of the expected number with mild hyperphenylalaninemia. Developing a national registry, as well as screening women who utilize birth control clinics or prenatal clinics, may be helpful. Implementing routine umbilical cord blood screening programs may be beneficial in efforts to identify women with hyperphenylalaninemia who have had a child and may want more children in the future.

Adolescent↗
PubMed1987

Folinic acid therapy in treatment of dihydropteridine reductase deficiency.

We gave folinic acid to three siblings, and to a fourth child, who have or had dihydropteridine reductase (DHPR) deficiency. The youngest began folinic acid therapy in addition to neurotransmitter precursors and a phenylalanine-restricted diet at age 2 months, and at 2 years of age has near normal development without evidence of neurologic impairment. His older brother began similar treatment at 5 1/2 months of age, when early neurologic findings were evident. At age 6 years his mental retardation and neurologic impairment are less severe than reported in most patients with DHPR deficiency. Little improvement occurred in their sister, who first received treatment at 2 years of age, when she already had severe neurologic impairment. An unrelated boy with profound neurologic impairment showed subtle signs of improvement after he began treatment with folinic acid alone at age 9 years. These results provide evidence that folinic acid is important in the treatment of DHPR deficiency and, if begun early in infancy, may prevent irreversible neurologic damage. The mechanism of folinic acid action in DHPR deficiency may be to increase indirectly the synthesis of 5-methyltetrahydrofolate.

5-Hydroxytryptophan↗
PubMed1987

New England Maternal PKU Project: prospective study of untreated and treated pregnancies and their outcomes.

Four women with classic phenylketonuria (blood phenylalanine greater than 1200 mumol/L) were given a phenylalanine-restricted diet; three also received L-tyrosine supplements. Biochemical measures of nutrition were normal except for iron deficiency anemia, and in one woman folate deficiency. One pregnancy in which treatment began before conception and another treated from 8 weeks gestation, both with blood phenylalanine levels maintained at 120 to 730 mumol/L, resulted in normal newborn infants whose postnatal growth and development have also been normal. A third pregnancy, treated from 6 gestational weeks, was marked by poor dietary compliance until the middle of the second trimester; fetal microcephaly was identified by ultrasonography at 28 weeks but not at 21 weeks. The child has microcephaly and motor delay. The fourth pregnancy, not treated until the third trimester, produced a child with microcephaly, mental retardation, hyperactivity, and neurologic deficits. It is likely that fetal damage from maternal phenylketonuria can be largely and perhaps entirely prevented by dietary therapy, but therapy must begin before conception for the best chance of a normal infant.

Adolescent↗
PubMed1987

Maternal phenylketonuria. Review with emphasis on pathogenesis.

Maternal phenylketonuria (PKU) refers to fetal damage from PKU in the pregnant woman. The progeny from such pregnancies are almost always microcephalic and mentally subnormal and have an increased frequency of congenital heart disease and low birth weight. Treatment with a phenylalanine-restricted diet, if begun before conception, seems to protect the fetus. The degree of protection is much less if dietary treatment is delayed until the pregnancy is in progress. The origin of fetal damage in maternal PKU is not known. Due to placental concentration of amino acids, the fetus is exposed to a higher concentration of phenylalanine than that in the mother, but it is not certain that phenylalanine is the toxic agent. Animal models made hyperphenylalaninemic by the administration of phenylalanine, often accompanied by a phenylalanine hydroxylase inhibitor, do not reproduce the full maternal PKU syndrome; but fetuses and newborns from these models have had reduced growth of the body and brain, and offspring later may show evidence of impaired learning ability.

Abnormalities, Multiple↗
PubMed1987

The Hartnup phenotype: Mendelian transport disorder, multifactorial disease.

The Hartnup mutation affects an amino acid transport system of intestine and kidney used by a large group of neutral charge alpha-amino acids (six essential and several nonessential). We compared developmental outcomes and medical histories of 21 Hartnup subjects, identified through newborn screening, with those of 19 control sibs. We found no significant differences in means of growth percentiles and IQ scores between Hartnup and control groups (but all low academic performance scores were found in the Hartnup group, and various skin lesions occurred in five Hartnup subjects), no significant difference between means of the summed plasma values for amino acids affected by the Hartnup gene in Hartnup and control groups, two Hartnup subjects with clinical manifestations--impaired somatic growth and IQ in one, impaired growth and a "pellagrin" episode in the other--who had the lowest summed plasma amino acid values in the Hartnup group; the corresponding values for their sibs were the low outliers in the control group, and two tissue-specific forms of the Hartnup (transport) phenotype: renal and intestinal involvement (15 families) and renal involvement alone (one family), both forms having been inherited as autosomal recessives (the symptomatic probands had the usual form). Whereas deficient activity of the "Hartnup" transport system is monogenic, the associated plasma amino acid value (measured genotype) is polygenic. The latter describes the parameter of homeostasis and liability to disease. Cause of Hartnup disease is multifactorial.

Amino Acids↗
PubMed1987

Predictors of intelligence quotient and intelligence quotient change in persons treated for phenylketonuria early in life.

Ninety-one individuals with phenylketonuria who were treated early in life were followed for as many as 22 years. Regression analyses were used to determine the best predictors of IQ and IQ change. Among treatment-related variables, good dietary control of the blood phenylalanine level stood out as the best predictor of IQ. Diet discontinuation and the natural (off diet) blood phenylalanine level best predicted IQ loss, suggesting that diet continuation may be important for children with natural blood phenylalanine levels greater than 18 mg/dL.

Adolescent↗
PubMed1986

Molecular analysis of the inheritance of phenylketonuria and mild hyperphenylalaninemia in families with both disorders.

Clinical phenylketonuria and mild hyperphenylalaninemia represent two different phenotypes of phenylalanine hydroxylase deficiency. To determine the genetic relation between these two phenotypes, we studied two families in which one member had phenylketonuria and other members had mild hyperphenylalaninemia. We identified restriction-fragment-length polymorphisms that differentiated the four phenylalanine hydroxylase alleles in each family. Phenylketonuria and mild hyperphenylalaninemia were found to be allelic; certain pairs of alleles induced the more severe phenylketonuria phenotype, and other pairs induced the less severe hyperphenylalaninemia phenotype. Several of the alleles that were identified can contribute to either phenylketonuria or mild hyperphenylalaninemia. These results demonstrate that there are multiple and distinct mutations in the phenylalanine hydroxylase gene, with different levels of severity, and that various combinations of the mutant alleles can result in different phenotypes of the metabolic disorders of hyperphenylalaninemia.

Alleles↗
PubMed1986

Maternal Hartnup disorder.

We describe childbearing in two unrelated women with Hartnup disorder, an inborn error of neutral amino acid transport. Two living, unaffected offspring born after untreated and uneventful pregnancies, one from each woman, have had normal growth and development. The older one had an IQ of 92 at 4 years while the younger one at 4 months had a Development Quotient of 107 on the Mental Scale and 102 on the Motor Scale. A third offspring had a neural tube defect complicated by hydrocephalus and died at 3 months. This mother had a family history of major congenital anomalies. We think that this experience supports the view that Hartnup disorder in the mother, unlike phenylketonuria, does not have an adverse effect on the fetus. The presence of normal ratios of the amino acid concentrations between maternal and umbilical veins in one mother also suggests that placental transport of free amino acids, unlike renal transport, may not be reduced in maternal Hartnup disorder.

Adult↗
PubMed1986

Bilateral lucency of the globus pallidus complicating methylmalonic acidemia.

A child was seen because of encephalopathy and metabolic ketoacidosis at 19 months. She was found to have a cobalamin-responsive form of methylmalonic acidemia of the cbl A complementation group. However, after treatment with cyanocobalamin and a protein-restricted diet, with recovery from the encephalopathy, she was found to have a tremor and bilateral dystonic posturing in association with lucencies in the globus pallidi shown by computed tomographic scan.

Brain Diseases↗