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Abstract: We report on an 18-year-old Lithuanian girl with hepatosplenomegaly noticed at birth, which progressed thereafter. The patient had to wait about 17 years for an accurate diagnosis and appropriate therapy. Lactase deficiency, congenital cataract of the right eye, and osteoporosis were observed. Episodes of drowsiness were caused by intake of high-protein food. Laboratory findings included slight hyperammonaemia, high plasma Citr, Ala, Gly, Glu, Ser levels, as well as citrullinuria, lysinuria, glutaminuria, alaninuria, argininuria, prolinuria, hydroxyprolinuria, ornithinuria, and orotic aciduria. A version to high-protein diet strongly suggested a disorder resulting in hyperammonaemia. Citrullinaemia was suspected. Subsequently the diagnosis of LPI was made on the basis of biochemical and clinical features. Molecular genetic testing revealed a mutation in theSLC7A7 gene, confirming the diagnosis.

We report the identification of two new 7‐year‐old patients with 3‐hydroxy‐2‐methylbutyryl‐CoA dehydrogenase deficiency, a recently described inborn error of isoleucine metabolism. The defect is localized one step above 3‐ketothiolase, resulting in a urinary metabolite pattern similar to that seen for deficiency of the latter. One patient has progressive neurodegenerative symptoms, whereas the clinical phenotype of the other patient is characterized by psychomotor retardation without loss of developmental milestones. A short‐term biochemical response to an isoleucine‐restricted diet was observed in both children.

Since 1973 the University Children's Hospital of Freiburg has provided a service devoted to selective screening for inborn errors of metabolism with particular emphasis on organic acidurias. Patients to be investigated are preselected by local clinical paediatricians. Between 1973 and the end of 1990, 46700 specimens from approximately 40000 patients were screened by the methods listed in Table 1. A total of 464 cases were found consisting of 51 different diseases, 242 cases of 23 different organic acidurias and 222 cases of 28 other inborn errors of metabolism. The number of cases diagnosed parallels the number of patients investigated showing that there is still a real demand for metabolic screening. The number of children to be investigated is stedily increasing. Using the presented and already published data an appraisal of the overall incidence of all organic acidurias (1∶6700) has been made as well as of the frequencies of the most common types of these disorders.