Hartnup disease masked by kwashiorkor.

This report describes an 11-month old girl with Hartnup disease presenting with kwashiorkor and acrodermatitis enteropathica-like skin lesions but free of other clinical findings. This case with kwashiorkor had acrodermatitis enteropathica-like desquamative skin eruption. Since zinc level was in the normal range, investigation for a metabolic disorder was considered, and Hartnup disease was diagnosed.

A clinicobiochemical study of tryptophan and other plasma and urinary amino acids in the family with Hartnup disease.

Two cases of Hartnup disease were diagnosed in a five member family. A changeable polymorph and severe clinical features of a 16 year old girl was described. Total plasma amino acids value was significantly decreased in the girl compared to the sum of plasma amino acids value in the brother, mother, father and to the summed maximal values of normal range. Intermediate aminoaciduria was also found with atypical amino acids pattern. Total plasma amino acids concentration was significantly reduced (27.20%) in the mother, while no significant decrease in the son (1.83%) and father (7.51%) were found compared to the summed maximal values of normal range. In the clinicaly healthy father, 38 years of age, a gross aminoaciduria with atypical pattern of amino acids was also found. Urinary amino acids concentration in the son and his mother were rather normal, although low concentration of eight amino acids was found in the mother's urine. Cerebrospinal fluid 5-hydroxyindoleacetic acid level was reduced in the girl.

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.

Occurrences of methylmalonic aciduria and Hartnup disorder in the same family.

Methylmalonic aciduria and Hartnup disorder are two rare autosomal recessively inherited metabolic disorders. We have described the coexistence of these disorders within the same pedigree in two unrelated families. This association was not found in 57 other families surveyed because of a proband known to have either methylmalonic aciduria or Hartnup disorder.

Natural history of Hartnup disease.

Hartnup disease was diagnosed in 12 children and 3 of their 15 sibs in the course of routine urine screening of 6-week-old infants in New South Wales. These children were followed for up to 8 years, during which time there were only two clinical episodes which might be ascribed to Hartnup disease. The mental development of all the children was normal. 10 had height centiles less than the midparent height centiles, while 4 had centiles equal to or above the midparent centiles. The study shows that in children with Hartnup disease in Australia symptoms are very uncommon. Mental development is normal, and heights are possibly slightly below that expected. Hartnup disease has an incidence of approximately 1 in 33 000 in New South Wales.

[Routine screening for inborn errors using urine filterpaper specimens at age 4-5 weeks (author's transl)]. / Routinemässiges Harm-Zweitscreening aus harngetränktem Filterpapier

Since 1972 we have been using a urine screening for the detection of inborn errors of amino acid metabolism, which cannot be revealed in newborn-blood-screening with Guthrie's bacterial inhibition assay. It is performed at an age of 4-6 weeks by means of thin layer chromatography of urine specimens collected on filter paper using a method adapted by us for mass-screening. We tested 70,400 newborns and found 59 cases of incomplete Cystinuria, 9 of Prolinuria, 3 of Histidinaemia and one each of Hartnup disease, Alkaptonuria, Glycinuria and Hydroxyprolinuria. The problems of the disorders found are discussed. Comparison with newborn-blood-screening that 3 cases of Histidinaemia, proven by enzyme assay were missed by newborn-blood-screening because of their (still low) low blood levels. On the other hand we did not find additional cases of phenylalanine-metabolic disorders. These cases were probably all already detected by newborn-blood-screening. Homocystinuria, Maple syrup urine disease and Arginino-succinicaciduria which are rare diseases were neither found in the urine or blood tests. As disorders, detectable by means of urine screening exclusively and curable, are rare urine screening has to be reevaluated for its usefulness.

Cellular transport of L-histidine in Hartnup disease.

The urinary excretion, the intestinal absorption, and the elimination of histidine from blood were studied in two patients with Hartnup disease. On standard diet the patients lost a great proportion of the dietary histidine in the urine, whereas the fecal loss was negligible. A high oral dose of L-histidine gave only a slight increase in plasma histidine and no increase in fecal histidine, but a considerable increase in the urinary histidine output. Intravenously administered L-histidine was eliminated more rapidly than in controls. The lack of increase in plasma histidine after the oral loading may be explained by the rapid elimination from the blood. This was mainly due to a rapid cellular uptake of histidine which is supposed to be a normal reaction of histidine-deprived cells. Thus the only obvious defect in the histidine transport in Hartnup disease is the reabsorption defect in the renal tubules. A generally impaired cellular transport of L-histidine is improbable.