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J G Gilman

Publications and source records attributed to J G Gilman.

At least 19 recordsLinked to original sources
PubMed1992

The 32.6 kb Indian delta beta-thalassaemia deletion ends in a 3.4 kb L1 element downstream of the beta-globin gene.

The Indian delta beta-thalassaemia, with elevated fetal gamma globin gene expression, was previously found to have a large deletion beginning 1 kb 3' of the (A) gamma globin gene at GenBank HUMHBB coordinate 42151, and extending into a new L1 sequence. We have now determined the 3' breakpoint of this deletion, and in doing so we have extended the known beta-globin gene cluster DNA sequence from its end at 73326 to projected GenBank coordinate 79016. These data show that the deletion is 32.6 kb long, terminating 11 kb 3' of the beta-globin gene. This 3' breakpoint is at 74772, within a 3.4 kb partial L1 repeat at 74263-77665; the Black ((A) gamma delta beta)(0)-thalassaemia also terminates in this L1, at 76508. In addition, two Alu sequences were found, at 73692-73816 and 78171-78441. Among the protein-binding DNA sequence motifs 3' to the Indian delta beta-thalassaemia breakpoint, at 76581/76607 there is a TGATAA/ACACCC pair that binds the erythroid-specific GATA-1 and ubiquitous CACCC-box binding proteins. We hypothesize that elevated fetal haemoglobin may be due to an enhancer or enhancers 3' to the deletion breakpoints and may involve the TGATAA/ACACCC pair.

Base Sequence↗
PubMed1991

Diminished A gamma T fetal globin levels in Sardinian haplotype II beta 0-thalassaemia patients are associated with a four base pair deletion in the A gamma T promoter.

In Sardinia, the beta-39 nonsense mutation is the primary cause of beta 0-thalassaemia. This mutation is found mainly on beta-globin gene cluster haplotypes I and II, which differ in their A gamma globin types (A gamma I and A gamma T, respectively). This report presents data on G gamma, A gamma I and A gamma T levels, and the presence or absence of a 4 base pair (bp) deletion at -225 to -222 of the A gamma globin promoter, in 55 poly-transfused beta 0-thalassaemia major patients. Six patients were homozygotes for the normal (N) A gamma promoter lacking the 4 bp deletion, had no A gamma T globin, and their mean G gamma:A gamma I: A gamma T ratio was 52.9:47.1:0. Twenty-five patients were homozygotes for the mutant (M) A gamma promoter with the 4 bp deletion, had no A gamma I globin, and the mean G gamma:A gamma I: A gamma T ratio was 62.1:0:37.9. For M/M compared to N/N, the lower A gamma T than A gamma I was significant by the t-test (P less than 0.001). Twenty-four N/M cases had mean G gamma:A gamma I:A gamma T of 56:24.4:19.6, and the lower A gamma T than A gamma I was also significant (P less than 0.001). Partial haplotype analysis on these and 17 other beta 0-thalassaemia patients suggested that the 4 bp deletion was strongly associated with haplotype II. Of 33 M/M, 32 were haplotype II/II and one was II/5a; of 31 N/M, 29 were I/II and two were II/IX; of eight N/N, seven were haplotype I/I and one was I/IX. These data show a strong association of the 4 bp promoter deletion with decreased expression of the A gamma T globin gene on haplotype II.

Base Sequence↗
PubMed1991

G gamma and A gamma globin genes are identical from -471 of the promoter midway through gamma IVSII in a Benin beta s haplotype associated with elevated fetal hemoglobin.

In seven kindreds in which sickle cell (SS) patients had elevated (greater than 12%) fetal hemoglobin (Hb F), Milner and colleagues reported that a determinant for elevated Hb F and elevated F cells was linked to the beta s gene. Independently, the Senegal (SEN) beta s haplotype has been found in association with elevated Hb F in SS and beta-thalassemia patients. We have used the kindreds of Milner and colleagues to characterize further the association of haplotype and gamma gene DNA sequence variation with Hb F expression. For the largest kindred, Wi, all four SS had high (greater than 14%) Hb F and both SEN and Benin (BEN) haplotypes. Two AS cases carrying SEN had low Hb F and low F cells, while three AS and one CS carrying BEN had elevated Hb F and elevated F cells; only one AS carrying BEN had low Hb F and low F cells. In order to look for genetic alterations that could account for the elevated Hb F of kindred Wi, we sequenced both the G gamma and A gamma genes of the Wi BEN haplotype. The data showed largely identical G gamma and A gamma genes which may have been generated by two gene conversions: the A gamma promoter was like that of G gamma 3' to -471, while the G gamma IVSII was like that of A gamma in its 5' half. In addition, three new mutations were found in gamma IVSII.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia, Sickle Cell↗
PubMed1990

Polymerase chain reaction amplification applied to the direct detection of a 4 bp deletion in the promoter region of the A gamma gene.

We report here the identification of a 4 bp deletion in the A gamma T globin gene promoter by means of Fnu4HI digestion of DNA amplified by polymerase chain reaction (PCR). This deletion has been previously associated with haplotype II beta-thalassemia in Sardinia. This simple, non-radioactive procedure should facilitate the screening of various populations of normal and beta-thalassemic subjects for this specific genetic alteration.

Chromosome Deletion↗
PubMed1989

The DNA deletion in an Indian delta beta-thalassaemia begins one kilobase from the A gamma globin gene and ends in an L1 repetitive sequence.

High fetal haemoglobin levels of 5-15% are present in adult heterozygotes for delta beta-thalassaemia as the result of large deletions of DNA. We have cloned DNA spanning the deletion breakpoint for a new Indian delta beta-thalassaemia associated with mild anaemia. The 5' breakpoint is at 42151 of GenBank file HUMHBB, which is about 1 kb 3' of the A gamma globin gene poly A site at 41003. On the 3' side of the breakpoint, the sequence is homologous to L1 (KpnI) repetitive DNA located 3.6-10 kb 3' of the beta-globin gene: Indian delta beta-thalassaemia DNA is 74% homologous to the inverted complement of HUMHBB from 69849 to 70020, followed by a region 78% homologous to the direct sequence of HUMHBB from 70534 to 71010. The precise location of the 3' endpoint of this deletion has not been determined, but it is within L1 sequences located more than 10 kb 3' of the beta-globin gene.

Base Sequence↗
PubMed1988

Distal CCAAT box deletion in the A gamma globin gene of two black adolescents with elevated fetal A gamma globin.

Point mutations in G gamma and A gamma globin gene promoters are associated with increased production of G gamma and A gamma globin, respectively. To determine whether an upstream promoter mutation could account for elevated A gamma in a Black adolescent with A gamma-beta+-HPFH and sickle cell trait, we cloned the 13 kb BglII fragment containing both gamma genes into phage lambda vector EMBL3. For one clone, the A gamma upstream promoter showed no hybridization to a 19 bp oligonucleotide whose sequence centered at -117. A gamma promoter sequence data for this mutant clone revealed a 13 bp deletion which eliminated the A gamma distal CCAAT box. Amplified A gamma genomic DNA of this and a similar case showed hybridization to both deletion-mutant and normal oligonucleotide probes. We propose that this 13 bp deletion removes part of the binding site for a repressor protein which is abundant in adult erythroid cells.

Adolescent↗
PubMed1988

Four base-pair DNA deletion in human A gamma globin-gene promoter associated with low A gamma expression in adults.

Fetal haemoglobin (alpha 2 gamma 2) is predominant in red cells of the fetus and newborn baby, and is largely replaced after birth by adult haemoglobin (alpha 2 beta 2). The two types of gamma chains (A gamma and G gamma) are generally less than 1% of total beta-like chain in adults, and the G gamma: A gamma ratio is typically 40:60. Higher G gamma values (greater than 50% of gamma chain) are frequently associated with a T for C nucleotide substitution 158 base pairs 5' of the G gamma Cap site (-158). The first exception to this rule was a beta o-thalassaemia in a Black family that was associated with about 60% G gamma in heterozygotes. A DNA fragment containing the G gamma and A gamma genes of the high G gamma haplotype of this case has now been cloned. DNA sequencing from -383 to the Cap site showed no differences from normal for the G gamma gene, except for C at -158. For the A gamma gene, however, a deletion of four base pairs (AGCA) at -222 to -225 was found. It is hypothesized that this deletion causes reduced A gamma globin gene expression in adults, which suggests that promoter elements important for the regulation of fetal haemoglobin expression in adults extend upstream at least to -225.

Adult↗
PubMed1988

Expression of G gamma and A gamma globin genes in human adults.

Expression of the human fetal G gamma and A gamma globin genes declines shortly after birth, and adults generally have less than 1% fetal hemoglobin or Hb F (alpha 2 gamma 2). However, some adults with hereditary persistence of fetal hemoglobin (HPFH) have elevated expression of either the G gamma or A gamma gene due to a mutation in its upstream promoter. Mutations with strong effects on expression have been found at -175 and -202 of the G gamma gene and at -117, -196, -198 and -202 of the A gamma gene. Mutations at -158 and -161 of G gamma have weaker effects, which are observable primarily as increases in the G gamma:A gamma ratio. Published data are reviewed which suggest that the -158 mutation may lead to observable elevations of Hb F in SS and beta(0)-thal patients and occasionally in normal non-anemic individuals. These data also suggest that additional high Hb F determinants are linked to Benin, Bantu and Asian beta S haplotypes in some instances. A model based on data from SV40 is presented which suggests that specific DNA sequence motifs of the gamma globin gene may bind regulatory proteins. It is proposed that the -158 and -161 mutations have weak effects because they are located on the fringe of regulatory sequence motifs.

Adult↗
PubMed1988

Upstream promoter mutation associated with a modest elevation of fetal hemoglobin expression in human adults.

In hereditary persistence of fetal hemoglobin, Hb F (alpha 2 gamma 2) is elevated after birth. Screening of sickle cell patients has revealed a family with elevated Hb F and high A gamma values. The propositus was a sickle cell patient with approximately 25% Hb F and 68.4% A gamma. He was heterozygous for the Benin (#19) and Mor beta S haplotypes. Five AS relatives with the Mor haplotype had 2.5% +/- 0.9% fetal hemoglobin and 92.8% +/- 2.8% A gamma, whereas two with the Benin haplotype had normal fetal hemoglobin (0.5%). The Mor haplotype is thus associated with the elevated Hb F in this family. The 13-kilobase (kb) Bg/II fragment containing the G gamma and A gamma genes of the Mor haplotype was cloned, and the G gamma and A gamma promoters sequenced from -383 to beyond the Cap sites. The Mor G gamma gene was normal, but the A gamma gene had a unique C----T mutation at -202. A different mutation at -202 of G gamma (C----G) was previously detected by other researchers in association with considerably higher Hb F in AS cases (15% to 25%). These data suggest either that -202 mutations affect the G gamma and A gamma promoters differently or that different nucleotide substitutions at -202 have divergent effects. Alternatively, additional unknown mutations could cause the differences in gene expression.

Adolescent↗
PubMed1988

Four categories of gamma-globin gene triplications: DNA sequence comparison of low G gamma and high G gamma triplications.

The human fetal gamma chains are produced by closely linked G gamma and A gamma genes, and unequal crossing over between them leads to gamma gene deletions and triplications. Nine gamma gene triplications from seven ethnic groups were analyzed for G gamma and hemoglobin F (Hb F) values of heterozygotes and for the presence of polymorphic XmnI restriction sites 5' to the gamma genes. Four categories of triplication were found: I had low G gamma and low Hb F values and lacked XmnI sites 5' to the three gamma genes [---]. II had high G gamma and slightly elevated Hb F values but was also [---]. III was similar to II, except that XmnI was [+--]. IV had very high G gamma and slightly elevated Hb F values, and XmnI was [++-]. One case each of triplications I and IV were cloned into Charon 35. For both, the two 5' gamma gene code for G gamma chain, while the 3' gamma gene codes for A gamma chain. DNA sequencing showed that the unequal crossover occurred between 472 and 398 base pairs (bp) 5' to the gamma gene Cap sites (-472 and -398) for the type IV triplication and between -271 and codon 136 for the type I triplication. In addition, type I had a 4-bp deletion of AGCA from -225 to -222. The high G gamma values of the type IV triplication are explained by its -G gamma-G gamma-A gamma-gene arrangement and the XmnI sites 5' to the G gamma genes. We hypothesize that the low G gamma value of the type I triplication, which is also -G gamma-G gamma-A gamma-, is due to inactivation of the middle G gamma gene by the AGCA deletion at -225 to -222.

Adult↗
PubMed1987

The 12.6 kilobase DNA deletion in Dutch beta zero-thalassaemia.

The Dutch beta zero-thalassaemia has few clinical symptoms in homozygotes, elevated fetal haemoglobin (4-11%) in heterozygotes, and has a DNA deletion previously estimated as 10 kb which removes the beta-globin gene (Gilman et al, 1984). A DNA fragment containing the breakpoints of the Dutch beta zero-thalassaemia deletion has now been cloned. Sequencing across the deletion junction region showed the 3' endpoint to be about 3 kb further 3' than originally thought, so that the deletion covers 12.6 kb. The 3' endpoint lies in a region of Kpn I (L1) repeated sequences, which is also the case for several other deletions. A six bp region of homology (AAATTT) between the 5' and 3' normal sequences at the breakpoint may have contributed to the non-homologous recombination event that led to the Dutch beta zero-thalassaemia deletion. The 12.6 kb Dutch beta zero-thalassaemia deletion is now seen to be a member of a 12-13 kb size category of deletions which also includes two delta beta-thalassaemias.

Base Sequence↗
PubMed1987

DNA sequence analysis of the Dutch beta zero-thalassemia deletion.

The Dutch beta zero-thalassemia has relatively few clinical symptoms in the homozygote. Heterozygotes have levels of fetal hemoglobin (4-11%) comparable to delta beta-thalassemia, and much higher than in typical beta zero-thalassemia. To analyze this deletion, we have cloned the abnormal 10 kb Bgl II fragment that contains the delta-globin gene into phage lambda vector EMBL4. A Hind III-Xba I fragment that includes the endpoints of the deletion was subcloned into plasmid pUC 19 and partially sequenced by the dideoxy method. The sequence of the Dutch beta zero-thalassemia DNA is like that of normal 5' DNA to 8920 (the numbering system is from reference 2). The sequence from 8915-8920 is AAATTT, which is also the normal 3' sequence from 21537-21542. From this point on, the Dutch beta zero-thalassemia sequence is like that of the normal 3' DNA. The deletion is therefore 12.6 kilobases, rather than 10 as originally estimated. It is similar to several other beta-globin gene deletions in terminating in a region of Kpn I repeated sequences, and having several base pairs of homology between 5' and 3' sequences at the break points.

Base Sequence↗
PubMed1985

DNA sequence variation associated with elevated fetal G gamma globin production.

The percentage of G gamma chains in the Hb F of SS patients and beta-thalassemia heterozygotes is generally 40%, but some have 60% to 70% G gamma. To test the hypothesis that DNA sequence variation 158 base pairs 5' of the G gamma gene is associated with this variation in G gamma values, DNA was analyzed using the restriction endonuclease Xmn I (gamma IVS-II probe). Xmn I recognizes the sequence from -157 to -166 only if T is at position -158. Individuals from five families had T at -158 for G gamma genes in both chromosomes, and the mean G gamma value was 69.7% +/- 4.6% (SD). For 13 families, individuals with T at -158 for the G gamma gene of one chromosome had a G gamma value of 60.6% +/- 5.7%. With one exception, lack of T at -158 was associated with low G gamma values (39.6% +/- 4.0%). In low Hb F G gamma-beta+-HPFH, the Xmn I site was seen 5' to both G gamma and A gamma genes, which suggests that T at -158 is associated with elevated Hb F; Pst I digestion showed that the A gamma gene T producer G gamma globin, which accounts for high levels of G gamma (87-88%). Calculations show that T at -158 is associated with a three- to 11-fold increase in production per G gamma gene, which is an order of magnitude less than that associated with the previously identified -202 C----G substitution of high Hb F G gamma-beta+-HPFH.

Anemia, Sickle Cell↗
PubMed1984

Dutch beta 0-thalassaemia: a 10 kilobase DNA deletion associated with significant gamma-chain production.

A unique beta 0-thalassaemia in a Dutch family results in fetal haemoglobin expression comparable to that of delta 0 beta 0-thalassaemia. Haemoglobin analysis and restriction endonuclease mapping studies of DNA suggest that the beta-globin gene is entirely deleted, but that the delta-globin gene is intact. The 5' break point of the deletion is 3-4 kilobases 3' to the delta-globin gene, while the 3' break point is 6-7 kilobases 3' to the beta-globin gene (relative to the normal DNA restriction map). The result is a approximately 10 kilobase deletion of DNA whose 3' end point may lie very close to that for one delta 0 beta 0-thalassaemia, within a cluster of Kpn I-family repetitive sequences. The Dutch beta 0-thalassaemia deletion is thus the shortest one which, in the absence of additional chromosomal rearrangements, results in enhancement of gamma-chain synthesis above that seen for haemoglobin Lepore. These data support the hypothesis that the region of DNA 3' to the beta-globin gene may be important to the developmental regulation of fetal gamma versus adult beta chain production.

Chromosome Deletion↗