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C B Whitley

Publications and source records attributed to C B Whitley.

At least 37 records · Page 2Linked to original sources
PubMed1995

Molecular diagnosis of mucopolysaccharidosis type II (Hunter syndrome) by automated sequencing and computer-assisted interpretation: toward mutation mapping of the iduronate-2-sulfatase gene.

Virtually all mutations causing Hunter syndrome (mucopolysaccharidosis type II) are expected to be new mutations. Therefore, as a means of molecular diagnosis, we developed a rapid method to sequence the entire iduronate-2-sulfatase (IDS) coding region. PCR amplicons representing the IDS cDNA were sequenced with an automatic instrument, and output was analyzed by computer-assisted interpretation of tracings, using Staden programs on a Sun computer. Mutations were found in 10 of 11 patients studied. Unique missense mutations were identified in five patients: H229Y (685C-->T, severe phenotype); P358R (1073C-->G, severe); R468W (1402C-->T, mild); P469H (1406C-->A, mild); and Y523C (1568A-->G, mild). Non-sense mutations were identified in two patients: R172X (514C-->T, severe) and Q389X (1165C-->T, severe). Two other patients with severe disease had insertions of 1 and 14 bp, in exons 3 and 6, respectively. In another patient with severe disease, the predominant (> 95%) IDS message resulted from aberrant splicing, which skipped exon 3. In this last case, consensus sequences for splice sites in exon 3 were intact, but a 395 C-->G mutation was identified 24 bp upstream from the 3' splice site of exon 3. This mutation created a cryptic 5' splice site with a better consensus sequence for 5' splice sites than the natural 5' splice site of intron 3. A minor population of the IDS message was processed by using this cryptic splice site; however, no correctly spliced message was detected in leukocytes from this patient. The mutational topology of the IDS gene is presented.

Amino Acid Sequence↗
PubMed1994

A new mtDNA mutation in the tRNA(Leu(UUR)) gene associated with maternally inherited cardiomyopathy.

We report a new mutation, a C to T transition at nt 3303 of mtDNA, in seven members of a family with cardiomyopathy and myopathy: the proband and two siblings had fatal infantile cardiomyopathy, whereas in three maternal relatives the disease manifested later in life as sudden cardiac death or as mitochondrial myopathy with cardiomyopathy. The mutation was homoplasmic in all tissues (including blood) from the proband and her brother, but heteroplasmic in blood from five oligosymptomatic or asymptomatic maternal relatives. This mutation disrupts a conserved base pair in the aminoacyl stem of the tRNA(Leu(UUR)). None of 70 controls carried the mutation. Our data indicate that this mutation is the genetic cause of the disorder in this family, and confirm that the tRNA(Leu(UUR)) is a "hot spot" for mutations in mtDNA.

Adolescent↗
PubMed1994

Light and electron microscopic features of the liver in mucopolysaccharidosis.

The mucopolysaccharidosis (MPS) diseases lead to the accumulation of glycosaminoglycan in many tissues. In this study 19 MPS I, one MPS II, five MPS III, and two MPS VI patients underwent liver biopsy for light and electron microscopic examination. Electron microscopy was performed for all 27 specimens. Twenty-six specimens were studied by light microscopy, and the slides were stained with colloidal iron and alcian blue in 26 and six biopsy specimens, respectively. By hematoxylin-eosin stain 20 of 26 cases showed hepatocellular dilatation with rarefaction of the cytoplasm; the Kupffer cells were unremarkable. Twenty-four and 25 of the 26 biopsy specimens showed substantial colloidal iron staining of hepatocytes and Kupffer cells, respectively. The six biopsy specimens prepared with alcian blue stain showed no reactivity of any cell type. Electron microscopy revealed characteristic membrane-bound inclusions within the hepatocytes and Kupffer cells of all 27 biopsy specimens. Of 19 cases in which Ito cells were identified, 18 included cells containing similar inclusions. Twenty of 27 biopsy specimens also demonstrated the hepatocellular accumulation of lipid droplets. Although there were no absolute distinguishing features among the various MPS diseases, the two MPS VI cases showed glycosaminoglycan inclusions that were fewer in number, smaller, and contained more abundant lipofusion than those associated with the other MPS types.

Adolescent↗
PubMed1994

Dense peripheral corneal clouding in Scheie syndrome.

A 28-year-old woman with Scheie syndrome (MPS I-S) presented with the unusual feature of extremely dense peripheral corneal clouding, allowing maintenance of good central visual acuity. Characteristic systemic features, an abnormal electroretinogram result, and absent alpha-L-iduronidase activity confirmed the diagnosis despite the unusual corneal pattern of clouding.

Adult↗
PubMed1993

Metabolic correction and cross-correction of mucopolysaccharidosis type II (Hunter syndrome) by retroviral-mediated gene transfer and expression of human iduronate-2-sulfatase.

To explore the possibility of using gene transfer to provide iduronate-2-sulfatase (IDS; EC 3.1.6.13) enzyme activity for treatment of Hunter syndrome, an amphotropic retroviral vector, L2SN, containing the human IDS coding sequence was constructed and studied for gene expression in vitro. Lymphoblastoid cell lines (LCLs) from patients with Hunter syndrome were transduced with L2SN and expressed high levels of IDS enzyme activity, 10- to 70-fold higher than normal human peripheral blood leukocytes or LCLs. Such L2SN-transduced LCLs failed to show accumulation of 35SO4 into glycosaminoglycan (35SO4-GAG), indicating that recombinant IDS enzyme participated in GAG metabolism. Coculture of L2SN-transduced LCLs with fibroblasts from patients with Hunter syndrome reduced the accumulation of 35SO4-GAG. These results demonstrated retroviral-mediated IDS gene transfer into lymphoid cells and the ability of such cells to provide recombinant enzyme for intercellular metabolic cross-correction.

Base Sequence↗
PubMed1993

Long-term outcome of Hurler syndrome following bone marrow transplantation.

Previous reports suggested a therapeutic response of lysosomal storage diseases such as Hurler syndrome following bone marrow transplantation. However, a clearer understanding of outcome has awaited long-term follow-up. We evaluated prospectively 11 consecutive patients with Hurler syndrome receiving marrow from an HLA-identical sib donor between September 1983-October 1988. Follow-up evaluations included assessment of donor engraftment by restriction fragment polymorphism analysis, determination of leukocyte alpha-L-iduronidase level, measurement of lumbar cerebrospinal fluid (CSF) pressure, computerized tomography (CT) of the brain, and psychometric testing. In this series there was a survival rate of 9/11 (82%) with all survivors showing complete (7 patients) or partial (2 patients) donor engraftment. Prospective longitudinal evaluation of the 9 surviving children, now 3.8-8.9 years posttransplantation (median 5.5) demonstrated persistence of previously deficient leukocyte alpha-L-iduronidase at levels reflecting the donor genotype and degree of donor engraftment. Urinary glycosaminoglycan excretion declined to near-normal within 5 months of donor engraftment. Prior to treatment, 7 of 8 children studied were found to have occult intracranial hypertension (lumbar CSF pressure > 20 cm CSF); however, all surviving children attained normal or near-normal pressure within 18 months of donor engraftment. Longterm follow-up CT imaging of the brain did not show progressive volume loss (cerebral atrophy) after donor engraftment. Of 9 survivors, 4 children having a developmental quotient (DQ, Mental Development Index on Bayley Scales of Infant Development) above 80 prior to transplantation subsequently maintained IQ scores above this level. However, 5 patients with lower pretransplant DQ scores now have significant cognitive deficits and attention deficit hyperactivity disorder. Progressive brain damage resulting from communicating hydrocephalus may be prevented by successful engraftment. Early transplantation of children with Hurler syndrome who have normal intelligence is likely to have the clearest benefit because long-term intellectual outcome will be limited by brain damage which has occurred prior to treatment.

Bone Marrow Transplantation↗
PubMed1992

Assessment of iduronate-2-sulfatase mRNA expression in Hunter syndrome (mucopolysaccharidosis type II).

Eight unrelated patients with Hunter syndrome were investigated for expression of iduronate-2-sulfatase (IDS) mRNA by reverse transcription (RT) linked to polymerase chain reaction (PCR), or RT-PCR. The entire coding region was studied by amplification of two overlapping segments of 0.7 and 1.1 kb. Seven children with Hunter syndrome had PCR products indistinguishable in size from normal. One patient, with clinically severe disease, did not produce either IDS product although mRNA for a control gene was readily amplified. This method rapidly identifies patients having absent or qualitatively abnormal IDS mRNA and may be useful in investigating genotype-phenotype relationships.

Base Sequence↗
PubMed1992

Heterozygosity for the "DN allele" (G533-greater than A) of the beta-hexosaminidase alpha subunit gene identified by direct DNA sequencing in a family with the B1 variant of GM2-gangliosidosis.

A new patient having clinical, pathologic and biochemical features of the exceedingly rate B1 variant of GM2-gangliosidosis is described. This patient, of northern European (non-Ashkenazi) ancestry, is the first affected child of this ethnic background available for molecular genetic analysis; thus, she represented an opportunity to identify a new mutation associated with this phenotype or, conversely, to further characterize the DN allele of the hexosaminidase alpha gene (G533-greater than A) as a more widely distributed mutation not previously observed in this gene pool. As a means of rapid analysis, we report a strategy for PCR amplification and direct DNA sequencing of exon 5 of the hexosaminidase alpha gene, the most frequent site of mutations in this condition. With this technique, the father of the affected child was determined to be heterozygous for the DN allele, while the mother was found to have only the normal sequence in this region. This observation further extends the known geographic and ethnic distribution of this mutation, and suggests the likelihood that the DN allele has been derived by multiple independent mutational events.

Alleles↗
PubMed1992

Pathology of the liver in mucopolysaccharidosis: light and electron microscopic assessment before and after bone marrow transplantation.

Serial liver biopsies were obtained in 20 patients undergoing bone marrow transplantation (BMT) for mucopolysaccharidosis (MPS). The 13 patients with MPS I, one with MPS II, four with MPS III, and two with MPS VI underwent liver biopsy prior to and from 1 to 37 months after BMT. The amount of accumulated glycosaminoglycan (GAG) was assessed by semiquantitation of Kupffer cell staining with colloidal iron and by counting the number of hepatocellular GAG-containing lysosomes in electron micrographs. Eleven of 13 patients with MPS I achieved engraftment, and 10 of the 11 cleared the Kupffer cells and hepatocytes of GAG by 3 to 19 months post-BMT. Two patients with autologous recovery demonstrated persistent hepatocyte inclusions. The three patients with MPS II and MPS VI engrafted and showed clearance of hepatocyte and Kupffer cell GAG by 7 months after BMT. All four patients with MPS III engrafted. Although the Kupffer cells in these patients were cleared of GAG by 12 months after BMT, hepatocellular inclusions persisted in all four. For MPS I, II and VI, donor engraftment was associated with resolution of lysosomal storage material in donor-derived Kupffer cells and untransplanted hepatocytes, indicative of transcellular metabolic correction. Failure of hepatocyte clearance in one case of MPS I and all patients with MPS III suggested a diminished capacity of the graft-derived enzyme to enter the hepatocyte lysosomes in these patients.

Bone Marrow Transplantation↗
PubMed1991

Adams-Oliver syndrome revisited.

The occurrence of Adams-Oliver syndrome in a patient from the same geographic area as the first reported kindred led to follow-up of the original family, and to a survey of the literature. Of 81 cases in 32 families, there is an approximately equal distribution between sexes (38 males: 43 females). Vertical transmission in at least 8 families is consistent with autosomal dominant inheritance. The phenotype is variable with a range of mild-to-severe defects of the scalp and/or underlying bone. Despite large defects of the cranium, central nervous system abnormalities have not been found and intellectual development appears to be normal. Limb defects are usually limited to the digits, but may involve the long bones and are entirely absent in some obligate carriers of the gene. Cutis marmorata and tortuous, dilated scalp veins have been reported in association with the major head and limb defects, but also in isolation as a forme fruste phenotype. Thus, there is a broad range of variable expression ranging from cases with lethally hemorrhagic cranial defects and/or severe limb malformations, to patients without any apparent manifestations. Despite a phenotypic resemblance to isolated aplasia cutis congenita and to the syndrome of terminal transverse limb defects, Adams-Oliver syndrome appears to be causally distinct. While the underlying pathophysiologic mechanism remains unknown, it can be speculated that cranial vertex defects and malformations of the limbs represent field defects resulting from impaired circulation in "watershed" areas during a critical period of development.

Female↗
PubMed1990

Busulfan disposition in children.

Children receive busulfan orally as part of myeloablative therapy before bone marrow transplantation for malignant and nonmalignant conditions. Children have been reported to have a low incidence of severe toxicity and significant rates of failure to achieve full engraftment. We evaluated the disposition of busulfan in children between 2 months and 3.6 years of age with lysosomal storage diseases, leukemia, and immunodeficiency disorders receiving oral doses of 1 or 2 mg/kg using a gas chromatographic assay. Peak concentrations were lower than those previously reported for adults, ranging from 1.4 to 5.2 mumol/L. The harmonic mean of the elimination half-life was 92 minutes, which is only slightly faster than that for adults (140 minutes). However, the area under the curve ranged from 400 to 1,000 (715 +/- 240) mumol.min/L, substantially lower than in adults receiving 1 mg/kg (range, 710 to 5,100 mumol.min/L; mean +/- SD, 2,180 +/- 1,200). The apparent volume of distribution (assuming complete bioavailability) ranged from 0.28 to 3.53 L/kg (1.42 +/- 0.86), which is more than twice that reported for adults (0.60 +/- 0.42). Busulfan clearance rate normalized to surface area is twice as high in children (200 +/- 100 mL/min/m2) as it is in adults (95 +/- 54 mL/min/m2). Alterations in bioavailability (absorption or first pass elimination) or in actual volume of distribution may account for these differences in drug disposition. The observed differences suggest the need for separate phase I dose escalation studies in children with accompanying pharmacokinetic assessment.

Administration, Oral↗
PubMed1989

Ocular changes in the mucopolysaccharidoses after bone marrow transplantation. A preliminary report.

Metabolic correction and physiologic response were evaluated after bone marrow transplantation in mucopolysaccharidosis. Eleven patients were prospectively evaluated to determine the effect of bone marrow transplantation on the progressive ocular manifestations of these disorders. Follow-up of 0.6 to 2.8 years after successful donor stem cell engraftment showed that some patients had slow clearing of the corneal clouding, reduction of intracytoplasmic inclusions in the conjunctiva, resolution of optic nerve edema, and stabilized or improved retinal function as determined by electroretinography. These preliminary results suggest that early bone marrow transplantation may alter some of the progressive ophthalmic characteristics of the mucopolysaccharidoses. Long-term follow-up is necessary to determine if these early alterations in the ocular features are predictive of a prolonged functional improvement in the visual status.

Bone Marrow Transplantation↗
PubMed1989

Diagnostic test for mucopolysaccharidosis. I. Direct method for quantifying excessive urinary glycosaminoglycan excretion.

This direct method for quantifying excessive urinary glycosaminoglycan excretion exploits the specific binding of 1,9-dimethylmethylene blue (DMB). The procedure obviates cumbersome and labor-intensive procedures for separating glycosaminoglycans from other constituents of urine. Pediatric pharmaceutical formulations (except heparin), in concentrations expected in urine, do not interfere with spectrophotometry, nor does protein. Results can be expressed in terms of urinary creatinine; thus the test is applicable to very small urine specimens (0.1 mL), such as those obtainable from neonates. In a pilot study, results of the direct DMB test for 48 urine specimens agreed with the clinical diagnosis, and quantitative measurements correlated moderately (r = 0.76) with results of a commonly used procedure (carbazole-borate reactivity after precipitation with cetylpyridinium chloride). The present method was also used to assess metabolic correction in a patient with Hurler's syndrome after treatment by bone-marrow transplantation. This quantitative method surmounts the major technical problems of developing mass screening programs for infants, thus offering the potential for earlier diagnosis and treatment of mucopolysaccharidosis diseases.

Bone Marrow Transplantation↗
PubMed1989

Diagnostic test for mucopolysaccharidosis. II. Rapid quantification of glycosaminoglycan in urine samples collected on a paper matrix.

The direct 1,9-dimethylmethylene blue (DMB) method for quantifying sulfated glycosaminoglycan (GAG) in urine (Clin Chem 1989; 35:374-9) has been adapted to a convenient means for sample collection and transport as a test to identify individuals with mucopolysaccharidosis (MPS) storage diseases. Results correlated moderately well (r = 0.85) with those of a commonly used, but more laborious, quantitative method. In studying factors to maximize differentiation of pathological from normal values, we found that GAG excretion (expressed as milligrams GAG per gram creatinine) fits a logarithmic function with respect to age and varies markedly below age five years. This must be considered in developing normative values and forming diagnoses. Of 112 separate urine specimens obtained from 41 MPS patients representing the major MPS diseases, glycosaminoglycan excretion by all exceeded that for age-matched normal individuals. The convenience of this method allowed us to establish the first normative values for three-week-old infants (n = 435) found to have a mean glycosaminoglycan excretion of 179 (SD 86.3) mg of GAG per gram of creatinine. This method improves the diagnostic capability for those MPS diseases that have been particularly difficult to identify (Sanfilippo's syndrome and Morquio's syndrome), and may also provide a test for other disorders with previously unrecognized abnormal excretion of glycosaminoglycan (e.g., mucolipidosis and acromesomelic dysplasia). Most importantly, this MPS diagnostic test is unique in its suitability for mass screening of newborn infants.

Adolescent↗
PubMed1988

Resolution of obstructive sleep apnea in Hurler syndrome after bone marrow transplantation.

Hurler syndrome, a lethal inborn error of lysosomal metabolism, results from the systemic accumulation of glycosaminoglycan. The progressive deposition of glycosaminoglycan in tissues of the upper aerodigestive tract has been suspected as the cause of airway obstruction, and many children have required tracheostomy. In a 3-year-old patient with Hurler syndrome, polysomnography confirmed the clinical impression of obstructive sleep apnea. Biopsy of an enlarged tonsil demonstrated that more than half the tissue volume resulted from abnormal lysosomal inclusions in macrophages. Three months after transplantation, repeat testing demonstrated resolution of airway obstruction, and 6 months after transplantation, tonsil biopsy showed complete absence of lysosomal inclusions. Bone marrow transplantation produces effective metabolic correction for Hurler syndrome and may be life-saving for patients with obstructive apnea.

Airway Obstruction↗