The reference OMIM entry for this protein is 219500

Cystathioninuria
Cystathionase deficiency

A number sign (#) is used with this entry because cystathioninuria is caused by homozygous or compound heterozygous mutation in the gene encoding cystathionine gamma-lyase (CTH; 607657) on chromosome 1p31.

DESCRIPTION

Cystathioninuria, an autosomal recessive phenotype with no striking pathologic features, is characterized by abnormal accumulation of plasma cystathionine, leading to increased urinary excretion. Because of the inconsistency and wide variety of disease associations, cystathioninuria is considered to be a benign biochemical anomaly (Mudd et al., 2001).

BIOCHEMICAL FEATURES

During a survey by paper chromatography of amino acids in the urine of patients in an institution for mental defectives, Harris et al. (1959) discovered a case with abnormal excretion of cystathionine. An inborn error involving the cleavage of cystathionine to give cysteine and homoserine was suggested. The subject was a severely retarded female, aged 64 years at the time of study. However, the metabolic disorder may have been fortuitously associated with mental retardation. Another case was studied at The New York Hospital. Other clinical manifestations have been clubfoot, developmental defects about the ears, convulsions, and thrombocytopenia. Urinary lithiasis also occurs. Mongeau et al. (1967) described the case of a 2-year-old boy with normal mentality, thrombocytopenia, and urinary calculi. The relation of the latter two features to the metabolic defect was problematic. Both parents (who were apparently unrelated) showed cystathioninuria after methionine loading test. With administration of pyridoxine, cystathioninuria was diminished in the proband. Schneiderman (1967) studied 2 mentally retarded brothers who excreted large amounts of cystathionine after methionine ingestion. The mother and another brother excreted lesser but abnormal amounts after methionine loading. The father was not tested. Perry et al. (1968) discovered cystathioninuria in a brother and sister when the brother's urine was by chance subjected to 2-dimensional paper chromatography for amino acids. Both children were normal. The parents excreted cystathionine only after methionine loading. The authors suggested that mental defect and other disorders reported in association with cystathioninuria may have been coincidental. Whelan and Scriver (1968) also found cystathioninuria as an apparently benign inborn error. Observations of cystinuria in connection with neuroblastoma (Klein et al., 1987) may derive from a secondary effect of the tumor process. Among cases of primary cystathioninuria, there are biochemical differences, such as variable response to methionine loading and/or B-vitamin treatment, suggesting the possibility of molecular genetic heterogeneity (Pascal et al., 1978; Tada et al., 1968). Espinos et al. (2010) reported 3 unrelated Spanish girls with cystathioninuria. They were investigated because of neurologic problems, and the relationship between the cystathioninuria and clinical abnormalities may have been due to ascertainment bias. Two girls had mental retardation, 1 with seizures, and 1 had normal intelligence but showed tremor. All had increased urinary cystathionine at the time of the study. Two had mildly increased plasma homocysteine. Oral pyridoxine treatment normalized the biochemical parameters, but resulted in only partial clinical improvement in the 2 mildly affected individuals. None of the patients had sibs, and all parents were una ... More on the omim web site

Subscribe to this protein entry history

June 30, 2020: Protein entry updated
Automatic update: OMIM entry 219500 was added.

Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).