Evidence for a null allele at the esterase D (EC 3.1.1.1) locus

Molecular analysis of the human esterase D gene ESD(*)Q0(yonago) responsible for incompatibility in a Japanese paternity case

In a Japanese paternity test, an alleged father was excluded only by reverse homozygosity of esterase D (ESD) phenotypes (mother, ESD 1; child, ESD 1; alleged father, ESD 2) out of 43 classical and DNA markers investigated. To solve the aberrant inheritance of the ESD phenotypes observed between them, fragments for all eight coding exons amplified by polymerase chain reaction (PCR) were subjected to DNA analysis. The child and alleged father shared a null allele, originating from ESD(*)1. It was characterized by having TGA for the stop codon instead of TCA for serine at codon 63. Thus, the sharing of a rare null gene, ESD(*)Q0(yonago), increased the probability of paternity.

Molecular analysis of esterase D polymorphism

We have analyzed the esterase D (EsD) polymorphism at the nucleic acid level. Two common alleles, EsD1 and EsD2, are characterized by the substitution of one amino acid (Gly-to-Glu), which is caused by the point mutation of one nucleotide (G-to-A). Individuals exhibiting the EsD1 and EsD 2 phenotypes are homozygotes for EsD 1 and EsD 2 cDNAs, respectively. Individuals showing the EsD 2-1 phenotype have two kinds of cDNAs, viz., EsD 1 and EsD 2. The point mutation difference between the cDNAs of the EsD1 and EsD2 alleles results in a different SspI digestion site. A restriction fragment length polymorphism caused by this difference with respect to the SspI digestion site makes it possible to determine the EsD phenotype using DNA samples extracted from forensic materials with no EsD enzymatic activity.

De novo 13q partial duplication identified by cytogenetic, biochemical and molecular approaches

A 3.5-month-old female infant manifesting dysmorphic facies, developmental delay and failure to thrive was referred for cytogenetic evaluation. Peripheral lymphocytes revealed three chromosomally distinct cell lines: 46,XX/46,XX,10p+/47,XX,10p+,+mar. Dermal fibroblasts revealed only the 46,XX,10p+cell line. High resolution G-, R-, and Q-banding suggested that the extra chromosomal material (10p+) represented a duplication of the segment 13q14----13qter. Parental karyotypes were normal. As absolute identification of de novo chromosomal abnormalities, based solely on cytogenetic studies, is sometimes difficult, both biochemical and molecular approaches were undertaken to elucidate this abnormality in more detail. Dosage effects were examined using esterase D (localized to 13q14.1) and the DNA probes p1E8 and p9A7 (localized to 13q22 and 13q31/32, respectively). These studies suggested the presence of only 2 copies of esterase D, but 3 copies of both DNA probes, allowing identification of the breakpoint at 13q14.2.

Involvement of the region 13q14 in a patient with adamantinoma of the long bones

A cytogenetic analysis of a lung metastasis of an adamantinoma of the tibia, a rare tumor of the long bones, revealed a karyotype 52, XY, t(7;13)(q32;q14), +7, +12, +13, +19, +der(7) t(7;13), +der(13) t(7;13). The t(7;13) was found to be constitutional in the patient and was also present in peripheral blood lymphocytes of his unaffected father. However, both subjects displayed normal levels of esterase D enzyme activity.

One hundred years of retinoblastoma research. From the clinic to the gene and back again

Retinoblastoma (RB) has provided the prototype for the study of hereditary predisposition to cancer. An intraocular tumour of young children, it has both hereditary and sporadic forms. The familial form of RB is inherited as an autosomal dominant with high penetrance. In a small group of patients the identification of a constitutional deletion on the long arm of chromosome 13 indicated the location of the critical gene in region 13q14 Close linkage between the hereditary, non-deletion form of RB and the esterase-D gene, which is also located in 13q14, demonstrated that all hereditary forms of RB are due to defects in a gene at this locus. Analysis of the development of homozygosity for region 13q14 in sporadic tumours subsequently confirmed that probably all RB tumors are due to mutations in a single gene, RB1. Using molecular biological techniques a candidate gene has been isolated which maps to region 13q14 and which shows structural re-arrangements within tumour cells. Predisposing, hereditary mutations have also been shown to involve this gene thereby providing strong evidence for its authenticity. The isolation of DNA sequences from within this gene, which identify restriction fragment length polymorphisms, means that it is now possible to use them to carry out pre-natal diagnosis and identify individuals at high risk to tumour development.

Interstitial deletion of chromosome 13 involving the region 13q14

A patient with an interstitial deletion 13q14 is described who has decreased erythrocyte esterase D activity and who has not developed a retinoblastoma.

Historic review of retinoblastoma

Retinoblastoma was first described as a specific entity by James Wardrop in 1809, with enucleation as his suggested treatment. Histologic studies including those of Flexner and Verhoeff and subsequent electron microscopy have given insights into its pathogenesis. The establishment of cell lines of retinoblastoma, the "nude" mouse model, and other animal models have contributed additional information. Classic genetic and epidemiologic studies have led to a broad and intense interest in the tumor despite its relative infrequency. Attempts now in progress to identify and characterize the oncogene for retinoblastoma may prove to be the most exciting part of the history of retinoblastoma.

A null allele of esterase D is a marker for genetic events in retinoblastoma formation

The development of homozygosity or hemizygosity in the 13q14 region by deletion, mitotic recombination, or chromosomal loss has been interpreted as a primary event in retinoblastoma. This finding is consistent with the hypothesis that inactivation of both alleles of a gene located at 13q14.11 is required for tumorigenesis. Observations reported by Benedict and colleagues in one case of bilateral retinoblastoma, LA-RB 69, provided early evidence in favor of this hypothesis. By examining levels of esterase D, an enzyme also mapping to 13q14.11, it was previously inferred that one chromosome 13 was lost. Using a rabbit anti-esterase D antibody and the esterase D cDNA probe, we have found that low but detectable quantities of esterase D protein and enzymatic activity are present in tumor cells from LA-RB 69; fibroblasts from this patient contain two copies of the esterase D gene, indicated by heterozygosity at an Apa I polymorphic site within this gene; and tumor cells from the same patient are homozygous at this site, indicating loss and reduplication of the esterase D locus. These results demonstrate that one of the two esterase D alleles in this patient acted as a "null" or silent allele--that is, was present in the genome with markedly decreased protein expression. This mutant allele acted as a marker for tumor-associated loss of chromosome 13 heterozygosity, in concordance with previous proposals.

Chromosome 13 instability and esterase D expression in an osteosarcoma cell line

In order to assess the involvement of the 13q14 region in the development of osteosarcoma, both osteosarcoma tumor cells and normal tissue from a retinoblastoma patient previously used in restriction fragment length polymorphism studies, and sarcoma cells and normal fibroblasts from other tumor patients, have been investigated with respect to esterase D (E.C. 3.1.1.1) expression and chromosome pattern. In spite of an increased number of apparently normal chromosomes #13, a 50% reduction in esterase D activity in osteosarcoma cells from the retinoblastoma patient was observed. This suggests that loss of the RB1 gene or an OSRC gene closely linked to the ESD and RB1 gene loci is involved in the development of the osteosarcoma tumor. No reduction in esterase D expression was seen in four other sarcoma cell lines.

Effect of the esterase-D phenotype on its in vitro enzyme activity

Esterase-D phenotypes and in vitro activity have been measured in red blood cells from 258 retinoblastoma patients and 73 unaffected relatives. Individuals with the 1-1 and 2-1 phenotypes showed distributions of enzyme activity which were not significantly different from each other. Individuals with the 2-2 phenotype, however, consistently showed a 25-30% lower level of enzyme activity. These results demonstrate the importance of determining the esterase-D phenotype in individuals with low ESD activity who might otherwise be assumed to carry a chromosome deletion at the esterase-D locus. We have also shown that, in vitro, the ESD enzyme is unstable over relatively short periods of time which, if uncontrolled, can give rise to a large variation in measured enzyme levels. The addition of b-mercaptoethanol to the assay buffer, which stabilises the enzyme, results in more consistent values being obtained within the same ESD phenotype. This feature could account in part for much of the variability in enzyme activity observed between different individuals in other studies.

A sialic acid-specific O-acetylesterase in human erythrocytes: possible identity with esterase D, the genetic marker of retinoblastomas and Wilson disease

The "nonspecific" esterases are a family of enzymes that were originally identified because of their reaction with synthetic O-acetyl ester substrates. While the electrophoretic polymorphisms of these enzymes have been extremely useful for genetic studies, their biological functions have remained completely unknown. Esterase D is characterized by its reactivity with 4-methylumbelliferyl acetate. This enzyme has recently been of particular interest because of its tight linkage to the putative recessive gene causing retinoblastomas, and to the recessive gene causing Wilson disease. We describe here the partial purification of a human erythrocyte esterase that appears to be highly specific for O-acetylated sialic acids. We next present evidence that suggests that esterase D is identical to this sialic acid-specific O-acetylesterase. First, both activities copurify from human erythrocyte lysates through several different purification steps, each of which use different principles of separation. Second, both activities show a remarkably similar profile of inhibition with a variety of different agents. Third, they both show a nearly identical heat-inactivation profile. This cytosolic sialic acid-specific O-acetylesterase appears to be involved in the "recycling" of O-acetylated sialic acid molecules. Thus, esterase D may be the first nonspecific esterase for which a specific biological role can be predicted.

The esterase D polymorphism as revealed by isoelectric focusing in ultra-thin polyacrylamide gels

The polymorphism of human red cell esterase D (EsD) was studied using isoelectric focusing (pH 4-6) in ultra-thin polyacrylamide gels. Typing was possible without the EsD isozymes attaining true equilibrium focusing conditions. Using this single method, six phenotypes (EsD 1, 2-1, 2, 5-1, 5-2 and 5) could be recognized in the White population of south-east England. Family studies showed these to be controlled by three co-dominant alleles and the gene frequencies were calculated to be EsD1 0.8856; EsD2 0.0946 and EsD5 0.0198. For successful and reliable EsD typing by this method, the electrophoretic system must be carefully optimized with respect to the duration of electrophoresis and the temperature attained in the gel during the electrophoretic run.

Incidence and significance of a deletion of chromosome band 13q14 in patients with retinoblastoma and in their families

Ten unrelated retinoblastoma patients were studied cytogenetically with high-resolution prophase banding; two had a deletion of chromosome 13, band q14. Neither of the two patients had any of the congenital defects usually associated with 13q14 deletions. In patient A, the deletion was found to be de novo. Patient B was found to be mosaic for the 13q14 deletion with 54% of the lymphocytes examined having the deletion. This study indicates that the 13q14 deletion may occur in a significant portion of all retinoblastoma cases. Esterase D activity and isozymes were studied also. The significance of findings will be discussed.

Differential enzyme activities in human esterase D phenotypes

Red cell ESD activities have been determined in 78 individuals with ESD-1 phenotype, in 94 with ESD2-1 and in 28 with ESD-2 phenotype. The mean activities of these three groups were 276.7, 216.6 and 171.5 expressed as 10(-7) M methylumbelliferone produced/h/g Hb, respectively. The activities associated with a single ESD*1 gene are estimated to be 60% higher than ESD*2.

Location of the retinoblastoma susceptibility gene(s) and the human esterase D locus

Retinoblastoma occurs with increased frequency in children born with a deletion of the long arm of chromosome 13. Recent reviews have noted that the region 13q14 is consistently deleted in documented cases. Prometaphase and late prophase banding allowed Yunis and Ramsay to determine that a deletion in one patient included the sub-bands q14 . 12, q14 . 13, and q14 . 2, and a portion of q14 . 11 and q14 . 3. We report the results of similar cytogenetic techniques applied in the case of a 26 month old Caucasian female with unilateral retinoblastoma, moderate developmental delay, and subtle dysmorphology. Prometaphase banding of cultured skin fibroblasts revealed the karyotype: mos46,XX/46,XX,del(13)(q13 . 1q14 . 11). Only the sub-band q14 . 11 is deleted in both our patient and that of Yunis and Ramsay. The results are consistent with the localisation of the retinoblastoma susceptibility gene(s) in the sub-band 13q14 . 11. Electrophoretic analysis and activity assays of red blood cell esterase D are consistent with hemizygous expression of that marker in our proband. Comparison with published esterase D analyses in families with retinoblastoma permits the assignment of the esterase D locus to that same sub-band, 13q14 . 11.

Evidence for a "new" allele at the esterase D (E.C. 3.1.1.1.) locus

An apparently new EsD gene product (EsD*Düsseldorf) was detected by use of horizontal agarose gel electrophoresis (AGE), starch gel electrophoresis (SGE), and isoelectric focusing (IEF). The observed phenotype EsD (1-Düsseldorf) can be distinguished from any known EsD type.

Bilateral retinoblastoma with de novo constitutional balanced translocation t(2;9)(q11;p11)

The case of a 6-year-old boy with bilateral retinoblastoma (RB) and apparently de novo balanced translocation t(2;9)(q11;p11) is presented. The normality of 13q14 chromosome region has been confirmed using high resolution techniques and Esterase D assay. The hypothesis that this RB might be correlated to the translocation is discussed.

Separation of retinoblastoma and esterase D loci in a patient with sporadic retinoblastoma and del(13)(q14.1q22.3)

A chromosome 13 deletion in a patient with sporadic retinoblastoma appears to have separated the loci for retinoblastoma and esterase D. This study indicates that: (1) the retinoblastoma locus is distinct from the esterase D locus; and (2) the linear order of these genes is centromere-esterase D-retinoblastoma.

Franceschetti syndrome in a child with a de novo balanced translocation (5;13)(q11;p11) and significant decrease of hexosaminidase B

We report a previously undescribed case of a de novo balanced translocation t(5;13)(q11;p11) and Franceschetti syndrome in a 3-year-old girl. The hypothesis that this unusual association might not be coincidental but rather due to position effect is proposed. Moreover the significant decrease of hexosaminidase B activity suggests the localization of this gene on the 5q11 band.

Low incidence of deletion of the esterase D locus in retinoblastoma patients

Esterase D was quantitatively measured in the red blood cells from three patients from three separate kindreds who had abnormalities of chromosome 13. The esterase D activity was proportional to the number of copies of the q14 region of chromosome 13 present. These findings confirm published data localizing the esterase D gene to chromosome band 13q14, a region which is important in the etiology of retinoblastoma. Fifty-one additional retinoblastoma patients not known to have any chromosomal defect also underwent esterase D determination. In none of these patients did the esterase D measurement detect a 13q14 deletion. The normal esterase D levels in this series of 51 retinoblastoma patients suggest that deletion of an esterase D locus is infrequent in retinoblastoma patients. It must be noted that patients who are mosaics, with a 13q14 deletion in only a fraction of all somatic cells, could possibly have normal red blood cell esterase D levels. Further study is necessary to determine if esterase D determination of all retinoblastoma patients is a worthwhile clinical tool.

Quantitative variations in polymorphic types of human red cell esterase D

Human red cell esterase D was analysed quantitatively in Japanese samples. Among the three esterase D phenotypes there was a significant difference in catalytic activity, with an approximate ratio of 7:5:3 for EsD 1, EsD 2-1 and EsD 2. With a few inter-type individuals, the distribution of their activity values was plotted in a tri-modal curve. These results suggest that the esterase D system in human red cells is qualitatively and even quantitatively controlled by genes.

Patient with 13 chromosome deletion: evidence that the retinoblastoma gene is a recessive cancer gene

Although a constitutional chromosomal deletion including 13q14 has been found to date in all retinoblastoma patients whose esterase D activity is 50 percent of normal, one female patient has been found who has 50 percent esterase D activity in all normal cells examined but no deletion of 13q14 at the 550-band level. Therefore, she has the smallest constitutional chromosomal deletion within 13q14 that is associated with susceptibility to retinoblastoma. Two stem lines were identified in a retinoblastoma from this patient, and each one had a missing 13 chromosome. No detectable esterase D activity was found in the tumor, indicating that the normal nondeleted 13 chromosome was lost in both stem lines. Thus the data from this patient not only show that there is a total loss of genetic information at the location of the retinoblastoma gene within the tumor, but also imply that recessive genes may play an important role in the development of certain human tumors including retinoblastoma.

Retinoblastoma, deletion 13q14, and esterase D: application of gene dosage effect to prenatal diagnosis

Esterase D (ESD) gene dosage studies were performed on amniotic cells from a fetus at risk for del 13q14. The mother was a balanced carrier of an insertion in chromosome #20: 46,XXins(20;13)(p12;q1307q14.3). She had already given birth to a monosomic child with retinoblastoma (Rb) and to a phenotypically normal child trisomic for the same 13q14 segment. Both sibs displayed the expected proportionate gene dosage effects for ESD. A 153% value of ESD activity was found in the amniotic cells indicating unambiguously that the fetus was not monosomic for segment 13q14 and therefore not at increased risk for Rb. The mother delivered a phenotypically normal child who was confirmed to be trisomic for segment 13q14 by cytogenetic analysis and by gene dosage studies for ESD in cord blood cells and in lymphoblastoid cells.

The ESD polymorphism: further studies of the ESD2 and ESD5 allele products

Electrofocusing and agarose electrophoresis techniques both reveal polymorphism of ESD2, which may be subdivided into two different proteins, coded for by genes allelic to EDS* 1. After agarose electrophoresis, ESD2 is slightly more anodally located than ESD5, while the latter is considerably more acidic as revealed by electrofocusing in polyacrylamide gel slabs. Family studies have confirmed that each of the allele products behave as Mendelian characters; and the gene frequencies in a Norwegian population material are about 0.08 and 0.02 for the ESD*2 and ESD*5 alleles, respectively.

Gene carrier detection in retinoblastoma

Although the presence of the retinoblastoma (RB) gene is usually made obvious by bilateral RB tumors, unaffected relatives of RB patients and unilateral RB patients may also carry the gene. Patients with 13q14 deletion have RB, and segregation of RB with markers (Q-banding and Esterase D) on chromosome 13 can be studied in some two-generation RB families. Radiosensitivity of fibroblasts may be a marker or may be present only in chromosome 13 deletion patients. Growth properties of fibroblasts suggest that the RB gene itself is expressed in normal cells. Ultimately, gene-carrier detection may be achieved by defining gene expression, gene product, or by cloning the gene itself.

Regional assignment of genes for human esterase D and retinoblastoma to chromosome band 13q14

The expression of human esterase D was evaluated quantitatively and qualitatively in five persons with partial deletions or duplications of chromosome 13. The results showed that the locus of this enzyme is at band 13q14. Deletion of this same band in other subjects has been found previously to indicate a predisposition to the development of retinoblastoma, which was present in the four individuals in this study who had partial deletions of chromosome 13. Because of this close synteny, esterase D evaluation should aid in the diagnosis and genetic counseling of retinoblastoma.

[The phenotype "Rügen" in esterase D polymorphism: evidence for the existence of a new allele (EsD6) (author's transl)]

An electrophoretic phenotype of esterase D is described, detected in a family living in the Rügen island (Baltic Sea). This is the new phenotype 6-1.

Atypical segregation of esterase D: evidence of a rare "silent" allele EsD0

Electrophoretic study of esterase D in 1027 mother-child pairs showed an atypical segregation of EsD alleles in one pair. The family analysis confirmed the evidence of a 'silent' gene (EsD0), which was observed in child, mother and grandfather. R banding of the metaphasal chromosomes revealed the normal appearance of the No. 13 pair, and no deletion of homologues No. 13 was observed in this family.

Expression of esterase D and other gene markers in trisomy 13

A gene dosage effect was observed for esterase D in a patient with trisomy 13. Isoelectric focusing of hemoglobin from the same patient showed three unidentified bands. A gene dosage effect for several other enzymes was not observed in two other patients with trisomy 13.