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Objectives: The treatment for phenylketonuria (PKU) includes monitoring blood phenylalanine (Phe) levels on a regular basis. To reduce inconvenience to the patient and family, blood specimens on filter paper can be obtained at home and mailed to the clinic or analytical laboratory. For this reason, we validated an 8-min isothermal and isocratic HPLC method using the Hitachi L-8800 analyzer for quantitation of Phe and tyrosine (Tyr) from dried blood specimens (DBS)., Design and Methods: The method was worked out using DBS fortified with Phe and Tyr. For method comparison, blood samples from 31 PKU patients and 5 non-PKU volunteers were analyzed as DBS by HPLC using the Hitachi L-8800 analyzer, and compared both to plasma analyzed by HPLC and DBS analyzed using tandem mass spectrometry (MS/MS)., Results: For HPLC analysis of DBS, the within-run precision for Phe and Tyr was < or = 5.1% and < or = 4.5%, respectively, and total precision measured over a 3-month period was < or = 7.2% and < or = 8.7%, respectively. Correlation analysis was performed using results from fresh plasma analyzed by HPLC (r = 0.988 for Phe, r = 0.964 for Tyr) and from DBS analyzed by MS/MS (r = 0.960 for Phe, r = 0.942 for Tyr). Difference plots revealed good agreement between the HPLC and MS/MS methods., Conclusions: Determination of Phe and Tyr in DBS using this HPLC technique compares well with other methods. This technique with its short analytical time is convenient for monitoring patients with PKU and might be particularly useful in centers following many patients.

Studies were carried out to identify the cause of combined severe hypermethioninemia and moderate hyperhomocysteinemia in a cluster of 10 infants ascertained between 1999 and early 2001. Although several were thought initially to have cystathionine beta-synthase (CBS) deficiency and treated accordingly, CBS deficiency and other known genetic causes of hypermethioninemia were ruled out by assay of CBS activity in fibroblasts of four patients and by assays of plasma cystathionine and S-adenosylmethionine. Retrospective data on dietary methionine intakes and plasma concentrations of methionine and related metabolites established that the hypermethioninemia in nine of the 10 babies was related to ingestion of an infant protein hydrolysate formula, the methionine content of which had been increased from May 1998 to February 2001. The formula in question has now been reformulated and is no longer available. The 10th infant manifested similar metabolic abnormalities while receiving TPN containing excessive methionine. Brain MRI abnormalities indicative of cerebral edema, most marked in the cerebral cortex and posterior brainstem, occurred in two patients near times of extreme hypermethioninemia. Metabolic and MRI abnormalities resolved when the methionine intake decreased. A third infant had a normal MRI 1 day after the formula was changed. The possible relationship between extreme hypermethioninemia and cerebral edema is discussed and a working hypothesis offered to explain the relative sensitivity of the inferior colliculi, based upon the facts that this is the region most active in glucose utilization and that Na(+),K(+)-ATPase is inhibited by methionine and related metabolites.

Argininemia, a rare autosomal recessive urea cycle disorder, is caused by a deficiency of arginase, with resulting elevated plasma arginine and ammonia levels. Reports to date have focused little on the neurology of this disorder or the efficacy of treatments. A MEDLINE search revealed 25 previously reported cases, to which we have added two brothers who presented with late onset progressive spastic diplegia. Though their degree of enzyme deficiency was comparable, the severity of their phenotypic abnormalities differed substantially. With dietary therapy, both showed improved cognitive and motor function. Late metabolic crises occurred in both, resulting in death of the less severely affected brother. Based on analysis of our clinical database, we report on the full spectrum of neurologic abnormalities seen in argininemia with particular focus on the accompanying progressive spastic diplegia and its response to treatment; progressive decline in head growth; distinctive neuroradiologic findings; and life-threatening later complications. Current and potential future therapies and long-term outcome are summarized.

GM1 gangliosidosis (type 1) is a rare hereditary, autosomal recessive, lysosomal storage disease characterized by a marked deficiency of active acid beta-galactosidase resulting in accumulation of gangliosides and mucopolysaccharides in tissues. Disease status of newborns from affected kindreds may be diagnosed by placental examination. Typical findings include a characteristic vacuolar distension of the cytoplasm of syncytiotrophoblast and stromal Hofbauer cells. We report a case of unsuspected fetal storage disorder initially diagnosed by routine placental examination of a normal-appearing infant born to a previously unaffected family. Progressive, third-trimester oligohydramnios and fetal growth retardation had been documented by ultrasonography. Placental findings included vacuolization of syncytiotrophoblast, intermediate trophoblast, and stromal Hofbauer cells. Subsequent enzyme analysis confirmed the placental findings of storage disorder and diagnosed GM1 gangliosidosis.

Methylmalonic acidemia due to deficient synthesis of 5'-deoxyadenosylcobalamin was discovered in a mid-term fetus by culture of amniotic-fluid cells. Elevated concentrations of methylmalonic acid were also found in amniotic fluid and maternal urine. Treatment during the last nine weeks of gestation with large doses of vitamin B12 given to the mother reversed the increasing maternal excretion of methylmalonic acid, which was 23 mug per milligram of creatinine at 31 weeks' gestation. Just before delivery, the mother was excreting 5 mug, two to three times normal. At birth the methylmalonic acid content of the baby's urine (67 mug per milligram of creatinine) and serum (2.0 mug per milliliter) was only moderately elevated, and serum vitamin B12 concentration was very high. Acid levels rose in serum and urine in response to oral protein loading, but subsided after vitamin B12 administration. The infant is developing normally on a restricted protein diet alone at present. Prenatal therapy of methylmalonic acidemia is possible with large amount of vitamin B12 administered to the mother.

Ten patients with familial hyperlysinemia with lysine-ketoglutarate reductase deficiency, identified through newborn screening programs or family surveys, were selected for review. Ages ranged from 2 to 24 years when last examined. A low-protein diet had been administered to two patients, which reduced the plasma lysine levels from 20 mg per dl or more to about 12 mg per dl. The rest were untreated. Mental development was judged normal or above average in nine. Mildly subnormal performance in three was considered appropriate to family and social background. No adverse mental or physical effects could be attributed to the hyperlysinemia. A normal child has been born to a mother with hyperlysinemia, indicating that the fetus may develop normally despite exposure to high lysine levels.

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.

A 6-month-old girl developed intermittent dystonic posture of the legs and eczematous dermatitis without ataxia. Qualitative and quantitative urine amino acid testing confirmed the diagnosis of Hartnup disease. Cranial computed tomography, electroencephalogram, electromyogram/nerve conduction study, posterior tibial somatosensory evoked potentials, 24-hour electroencephalographic telemetry, and metrizamide myelogram were normal. Spinal fluid hydroxy-indoleacetic acid concentration was less than or equal to 2 S.D. of normal; oral tryptophan loading (70 mg/kg) resulted in a two-fold rise in cerebrospinal fluid 5-hydroxy-indoleacetic acid concentration. Tryptophan administered alone or with nicotinic acid failed to improve the dystonia; however, trihexyphenidyl (1-2 mg/kg/day) dramatically improved it. Hartnup disease should be considered in children with unexplained dystonia.

Newborn blood from three siblings with prolidase deficiency contained no detectable prolidase activity. Umbilical cord blood contained no prolidase activity in one sibling and only 6.8% of control activity in another sibling. In prolidase deficiency the enzyme defect is expressed at birth, well before the appearance of skin ulcers, and is demonstrable in filter paper specimens of blood obtained for routine screening.

beta-Mercaptolactate-cysteine disulfide, a hitherto undescribed analog of cystine, was isolated from the urine of a mentally retarded patient. The propertis of this substance are described, and its structure is confirmed by mass spectrometry and by partial synthesis.