Identification of the tuberous sclerosis gene TSC1 on chromosome 9q34.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the widespread development of distinctive tumors termed hamartomas. TSC-determining loci have been mapped to chromosomes 9q34 (TSC1) and 16p13 (TSC2). The TSC1 gene was identified from a 900-kilobase region containing at least 30 genes. The 8.6-kilobase TSC1 transcript is widely expressed and encodes a protein of 130 kilodaltons (hamartin) that has homology to a putative yeast protein of unknown function. Thirty-two distinct mutations were identified in TSC1, 30 of which were truncating, and a single mutation (2105delAAAG) was seen in six apparently unrelated patients. In one of these six, a somatic mutation in the wild-type allele was found in a TSC-associated renal carcinoma, which suggests that hamartin acts as a tumor suppressor.

Retinal degeneration characterizes a spinocerebellar ataxia mapping to chromosome 3p.

A heterogeneous group of neurological disorders known as the spinocerebellar ataxias (SCA) are characterized by degeneration of the cerebellum, spinal cord and brainstem. We describe linkage analysis in four unusual SCA families revealing a distinct disease locus on chromosome 3p14-21.1. The disease in these families is distinguished from other forms of SCA by concomitant retinal degeneration. Initial visual problems leading to blindness, disabling ataxia and anticipation are seen in all kindreds. The anticipation in these families suggests a dynamic mutation at this locus. Eventual molecular characterization of this disease may provide valuable insights into the processes of both neural and retinal degeneration.

Autosomal dominant cerebellar ataxia with retinal degeneration: clinical, neuropathologic, and genetic analysis of a large kindred.

The autosomal dominant cerebellar ataxias (ADCA) comprise a heterogeneous group of neurologic disorders characterized by degeneration of the cerebellum, spinal cord, and brainstem. Genetic analysis has revealed two loci, SCA1 on chromosome 6p, and SCA2 on chromosome 12q, responsible for some ADCA. We present a four-generation kindred of 42 individuals, 12 of whom were clinically affected with ADCA and an associated cone dystrophy. Early loss of color discrimination with retinal and macular signs is followed by gradual progression of cerebellar dysfunction and development of pyramidal signs. Pathology shows degeneration of cerebellum, basis pontis, inferior olive, and retinal ganglion cells. For genetic analysis, we used polymorphic markers D6S89 and D12S79; linkage analysis gave negative results, excluding linkage to both SCA1 and SCA2. The data strongly support genetic heterogeneity consistent with the unique clinicopathologic features of the form of ADCA displayed in this large family.

Isolation and characterization of Sporothrix schenckii from clinical and environmental sources associated with the largest U.S. epidemic of sporotrichosis.

The largest recorded epidemic of sporotrichosis in the United States occurred in 1988 and involved a total of 84 cases in 15 states. All cases were associated with Wisconsin-grown sphagnum moss. Twenty-one clinical isolates of Sporothrix schenckii and 69 environmental isolates of Sporothrix spp. from the epidemic were characterized and compared. The environmental isolates were recovered from 102 samples of sphagnum moss and other material by using direct plating techniques. Characteristics examined included macroscopic and microscopic morphology, conversion to a yeast phase, exoantigen reactions, and virulence in mice. On the basis of these studies, eight environmental isolates were identified as S. schenckii, five were identified as Ophiostoma stenoceras, and the remainder were identified as Sporothrix species. The environmental isolates of S. schenckii were recovered from moss samples from one Pennsylvania nursery and from three New York State Soil and Water Conservation districts, but none were recovered from moss directly from the bogs in Wisconsin.

Mucinous adenocarcinoma of the orbit arising from a stable, benign-appearing eyelid nodule.

Mucinous adenocarcinoma is a rare eyelid tumor which should be considered in the differential diagnosis of a nodular or cystic lesion of the eyelid. This lesion may be locally aggressive and requires complete excision to prevent local recurrence or regional metastases. We present what we believe is the first report of a mucinous adenocarcinoma manifesting as a stable, benign-appearing nodule that has already given rise to a much larger secondary lesion. This case underscores the importance of performing a biopsy on even benign-appearing eyelid nodules.

The ETS genes on chromosome 21 are distal to the breakpoint of the acute myelogenous leukemia translocation (8;21).

The definition of the genetic linkage map of human chromosomes may be helpful in the analysis of cancer-specific chromosome abnormalities. In the translocation (8;21)(q22;q22), a nonrandom cytogenetic abnormality of acute myelogenous leukemia (AML), we previously observed the transposition of the ETS2 gene located at the 21q22 region from chromosome 21 to chromosome 8. However, no ETS2 rearrangements were detected in the DNA of t(8;21)-positive AML cells. Genetic linkage analysis has allowed us to locate the ETS2 gene relative to other loci and to establish that the breakpoint is at an approximate genetic distance of 17 cM from ETS2. When the information from the linkage map is combined with that from molecular studies, it is apparent that (a) the t(8;21) breakpoint does not affect the ETS2 gene structure or the structure of the other four loci proximal to ETS2: D21S55, D21S57, D21S17, and ERG, and ETS-related gene; and (b) the actual DNA sequence involved in the t(8;21) must reside in a 3-cM genetic region between the D21S58 and the D21S55/D21S57 loci, and remains to be identified.

First report of subcutaneous phaeohyphomycosis of the foot caused by Phoma minutella.

Phoma minutella, a dematiaceous hyphomycete, was isolated to the exclusion of all other fungi from a subcutaneous inflammatory process on the foot of a farmer undergoing corticosteroid therapy for myasthenia gravis. Isolation was achieved on several nutrient media. Examination of stained smears and sections revealed dematiaceous fungal elements consistent with the mold. This is the first reported association of P. minutella with a human infection and only the second reported case involving a Phoma sp. as the etiologic agent of a subcutaneous infection.

A fatal poisoning from an amatoxin containing Lepiota.

The mushroom Lepiota josserandii Bon and Boif. has been identified as the cause of an unintentional, fatal intoxication in New York. The course of the symptoms, beginning with a 9 h latent period, was similar to what would be expected in a case of Amanita phalloides-type intoxication. Despite supportive medical care the victim expired 110 h after ingestion. Thin layer chromatography detected the presence of alpha- and gamma-amanitin and radioimmunoassay confirmed a level of 3.5 mg/gm dry weight of amatoxins in mushrooms from the same location.