Balanced translocations of 11q23 are associated with specific clinical features and a poor outcome, but the relevance of deletions involving 11q23 is not clear. Fifty-seven patients with this deletion were collected by the Workshop, 30 had terminal and 27 had interstitial deletions. Twenty-seven patients had acute lymphoblastic leukemia (ALL), 16 had acute myeloid leukemia (AML), one had acute biphenotypic leukemia, one had acute undifferentiated leukemia and 12 had myelodysplastic syndrome (MDS). ALL patients had a median age of 7 years, median white blood cell count (WBC) of 15 × 10 9 /l, and 10/24 had common ALL. AML patients had a median age of 23 years, a median WBC of 49 × 10 9 /l, and 9/16 had M4 or M5. MDS patients were all adult, median age of 69 years, median WBC of 3 × 10 9 /l, and 7/12 had refractory anemia. The clinical outcome depended on diagnosis: children with ALL had a better prognosis (4/16 relapsed, one died) than AML patients; all adults and children with AML and 5/12 MDS patients died. Fluorescence in situ hybridization (FISH) identified 3 del(11q23) as translocations or insertions. Molecular studies revealed a MLL rearrangement in 8/10 patients. Because the involvement of MLL might be of prognostic relevance, identification of a del(11q23) should be an indication for FISH and molecular studies.

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S-100 protein, which is found essentially in the astrocytes of the nervous system, was assayed in amniotic fluids by Particle Counting ImmunoAssay. It was present in 19 cases of anencephaly out of 26, in 1 case of open spina bifida out of 5 and in each of the 4 cases of fetal death, whereas it was not detected in the 48 control amniotic fluids collected between the 16th and the 35th week of gestation. Thirty-one amniotic fluids from fetuses with other congenital malformations were devoid of detectable S-100. The presence of S-100 in amniotic fluid of anencephalic fetuses can presumably be considered as a biological sign of necrosis of the exencephalic brain and seems specific to damage of the central nervous system accompanied by neural tube defect.

Metachromatic leukodystrophy (MLD) is an autosomal recessive disease of myelin metabolism caused by a deficiency in the lysosomal enzyme arylsulphatase A (ARSA). We have identified a new mutation in exon 4 of the ARSA gene of two unrelated Belgian patients with late-infantile MLD. The mutation predicts an aspartic acid-to-histidine substitution at position 255 in arylsulphatase A (D255H), in a highly conserved region among sulphatases. Transient expression of the mutation in COS cells did not show an increase in ARSA activity. Both patients were compound heterozygotes carrying the frequent splice site mutation in intron 2 (459 + IG -->A) on the other allele.