Increased very long chain fatty acids in patients on a ketogenic diet: a cause of diagnostic confusion.

We found an elevation of very long chain fatty acids in 13 of 22 plasma samples from patients on a ketogenic diet for the treatment of uncontrolled seizures. Because elevated values of very long chain fatty acids are a biochemical manifestation of peroxisomal dysfunction, this phenomenon might lead to diagnostic confusion. Thus the history and clinical status should be considered when plasma levels of very long chain fatty acids are interpreted.

Early manifestations of multiple sulfatase deficiency.

We describe two boys, presenting by 1 year of age, with developmental delay from birth, mildly coarse facial features, and hepatomegaly. These clinical features were most suggestive of a mucopolysaccharidosis, particularly MPS II. Biochemical studies, including sulfate incorporation in fibroblasts and lysosomal enzyme analyses in fibroblasts, leukocytes, and serum, showed abnormalities in both sulfatide and mucopolysaccharide metabolism and led to the diagnosis of multiple sulfatase deficiency. With time, both patients developed an ichthyotic rash and profound intellectual deterioration. We conclude that findings in the first year of life in some patients with MSD may closely resemble those in patients with a MPS disorder rather than the late infantile form of metachromatic leukodystrophy, as is classically described. Thus, MSD should be considered in the young patient suspected of having a MPS disorder.

Identification of female carriers of adrenoleukodystrophy.

The concentrations of very long chain fatty acids in plasma and cultured skin fibroblasts were studied in 96 women who were obligate heterozygotes for X-linked adrenoleukodystrophy, in 34 women who were mothers of single probands with ALD, and in 32 normal women of comparable age. Discriminant analysis was used to develop a classification function for the plasma values. With this function, plasma values in 88% of the women who were obligate heterozygotes for ALD and 77% of the mothers of single probands were identified as abnormal. With subsequent inclusion of the fibroblast assay data, abnormal plasma values were found in 93% of the obligate heterozygotes.

Diagnosis of lipogranulomatosis (Farber disease) by use of cultured fibroblasts.

The enzyme defect in Farber disease, a deficiency of acid ceramidase, has been demonstrated in cultured skin fibroblasts, which provides a means of confirming the diagnosis during life. The assay can also be performed using cultured amniotic fluid cells and is a potential tool for detection of carriers of the disease.