Contiguous Deletion of the X-Linked Adrenoleukodystrophy Gene (ABCD1) and DXS1357E: A Novel Neonatal Phenotype Similar to Peroxisomal Biogenesis Disorders

Division of Genetics, The Children's Hospital, Boston, Massachusetts, USA.
The American Journal of Human Genetics (Impact Factor: 10.93). 06/2002; 70(6):1520-31. DOI: 10.1086/340849
Source: PubMed


X-linked adrenoleukodystrophy (X-ALD) results from mutations in ABCD1. ABCD1 resides on Xq28 and encodes an integral peroxisomal membrane protein (ALD protein [ALDP]) that is of unknown function and that belongs to the ATP-binding cassette-transporter superfamily. Individuals with ABCD1 mutations accumulate very-long-chain fatty acids (VLCFA) (carbon length >22). Childhood cerebral X-ALD is the most devastating form of the disease. These children have the earliest onset (age 7.2 +/- 1.7 years) among the clinical phenotypes for ABCD1 mutations, but onset does not occur at <3 years of age. Individuals with either peroxisomal biogenesis disorders (PBD) or single-enzyme deficiencies (SED) in the peroxisomal beta-oxidation pathway--disorders such as acyl CoA oxidase deficiency and bifunctional protein deficiency--also accumulate VLCFA, but they present during the neonatal period. Until now, it has been possible to distinguish unequivocally between individuals with these autosomal recessively inherited syndromes and individuals with ABCD1 mutations, on the basis of the clinical presentation and measurement of other biochemical markers. We have identified three newborn boys who had clinical symptoms and initial biochemical results consistent with PBD or SED. In further study, however, we showed that they lacked ALDP, and we identified deletions that extended into the promoter region of ABCD1 and the neighboring gene, DXS1357E. Mutations in DXS1357E and the ABCD1 promoter region have not been described previously. We propose that the term "contiguous ABCD1 DXS1357E deletion syndrome" (CADDS) be used to identify this new contiguous-gene syndrome. The three patients with CADDS who are described here have important implications for genetic counseling, because individuals with CADDS may previously have been misdiagnosed as having an autosomal recessive PBD or SED

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    • "As far as we know, this is the first case report with a deletion of both the SLC6A8 and BAP31 genes. The phenotype of the BAP31 mutations has only been reported as part of Xq28 deletion syndrome or contiguous ATP-binding cassette, sub-family D, member 1 (ABCD1)/DXS1375E (BAP31) deletion syndrome (CADDS; MIM ID #300475) [16]. Patients with CADDS manifest with leukodystrophy due to an ABCD1 mutation. "
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    ABSTRACT: The BCAP31 gene is located between SLC6A8, associated with X-linked creatine transporter deficiency, and ABCD1, associated with X-linked adrenoleukodystrophy. Recently, loss-of-function mutations in BCAP31 were reported in association with severe developmental delay, deafness and dystonia. We characterized the breakpoints in eight patients with deletions of SLC6A8, BCAP31 and/or ABCD1 and studied the genotype-phenotype correlations. The phenotype in patients with contiguous gene deletions involving BCAP31 overlaps with the phenotype of isolated BCAP31 deficiency. Only deletions involving both BCAP31 and ABCD1 were associated with hepatic cholestasis and death before one year, which might be explained by a synergistic effect. Remarkably, a patient with an isolated deletion of the 3'end of SLC6A8 had a similar severe phenotype as seen in BCAP31 deficiency but without deafness. This might be caused by disturbance of a regulatory element between SLC6A8 and BCAP31.
    Clinical Genetics 03/2014; 87(2). DOI:10.1111/cge.12355 · 3.93 Impact Factor
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    • "Consistent with prior reports [42], cultured CCALD patient skin fibroblasts grown in fibroblast growth media showed 4.3-fold elevated VLCFA levels (based on C26:0-lysophosphorylcholine measurements, see Materials and methods), but similar PE plasmalogen levels relative to fibroblasts from healthy donors (Figure 3A, C)). Similarly, we found 3.8-fold elevated VLCFA levels, but comparable PE plasmalogen levels, in patients relative to control fibroblasts grown under the same conditions in iPSC media (Figure 3A, C). "
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    ABSTRACT: Introduction X-linked adrenoleukodystrophy (X-ALD) is a complex disorder with variable expressivity that affects the nervous, adrenocortical and male reproductive systems. Although ABCD1 mutations are known to provide the genetic basis for X-ALD, its pathogenesis is not fully elucidated. While elevated very long chain fatty acid (VLCFA) levels in blood and reduced VLCFA catabolic activity in cultured fibroblasts are biomarkers used to identify ABCD1 mutation carriers, the roles peroxisomal lipid metabolism play in disease etiology are unknown. Methods Primary skin fibroblasts from two male patients with the childhood cerebral form of the disease (CCALD) caused by ABCD1 frameshift or missense mutations and three healthy donors were transduced with retroviral vectors expressing the OCT4, SOX2, KLF4 and c-MYC factors. Candidate induced pluripotent stem cells (iPSCs) were subject to global gene expression, DNA methylation, DNA copy number variation, and genotyping analysis and tested for pluripotency through in vitro differentiation and teratoma formation. Saturated VLCFA (sVLCFA) and plasmalogen levels in primary fibroblasts and iPSCs from healthy donors as well as CCALD patients were determined through mass spectroscopy. Results Skin fibroblasts from CCALD patients and healthy donors were reprogrammed into validated iPSCs. Unlike fibroblasts, CCALD patient iPSCs show differentially expressed genes (DEGs) relevant to both peroxisome abundance and neuroinflammation. Also, in contrast to fibroblasts, iPSCs from patients showed no significant difference in sVLCFA levels relative to those from controls. In all cell types, the plasmalogen levels tested did not correlate with ABCD1 mutation status. Conclusion Normal ABCD1 gene function is not required for reprogramming skin fibroblasts into iPSCs or maintaining pluripotency. Relative to DEGs found in fibroblasts, DEGs uncovered in comparisons of CCALD patient and control iPSCs are more consistent with major hypotheses regarding disease pathogenesis. These DEGs were independent of differences in sVLCFA levels, which did not vary according to ABCD1 mutation status. The highlighted genes provide new leads for pathogenic mechanisms that can be explored in animal models and human tissue specimens. We suggest that these iPSC resources will have applications that include assisting efforts to identify genetic and environmental modifiers and screening for therapeutic interventions tailored towards affected cell populations and patient genotypes.
    Stem Cell Research & Therapy 10/2012; 3(5):39. DOI:10.1186/scrt130 · 3.37 Impact Factor
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    ABSTRACT: q28→pter)[14]/46,XX[1].nuc ish(CEPXx1)[30/100]/ (CEPXx2)[18/100]/(CEPXx3)[52/100]. Rasprava: Klinička obilježja bolesnice prikazana su i uspoređena s kliničkim obilježjima prethodno opisanih slučajeva izodicentričnog X kromosoma s točkom loma u kromosomskoj regiji Xq28. Iako je izodicentrični X kromosom rijedak genetički poremećaj, nužno je prepoznati žene s primarnom ili sekundarnom amenorejom, poremećajem rasta te eventualnim drugim prirođenim anomalijama koje upućuju na genetički uzrok već na razini primarne zdravstvene zaštite te ih što prije uputiti na specijalističku obradu kao i citogenetičku analizu zbog pravilnog genetičkog informiranja. Aim: Isodicentric X chromosome is a structural chromosome aberration which leads to ovarian dysfunction associated with primary or secondary amenorrhea. The variability of clinical features depends on the position of the breakpoint, mosaicism and pattern of X inactivation. We present a case of a patient with mosaic karyotype and isodicentric X chromosome with breakpoint in the region q28. Case report: The patient is a 47-year-old woman with secondary amenorrhea, obesity, tall stature and craniofacial dysmorphy. She had menarche at the age of 16 and no spontaneous menstrual cycles after the fourth cycle. The patient was diagnosed with hypergonadotropic hypogonadism and hormone therapy was introduced. The latest pelvic sonography detected a normally shaped and sized uterus and small ovaries of homogenous structure. The patient has been obese since childhood and her current weight is 144kg, height 180cm (BMI 44kg/m2). She has craniofacial dysmorphy including thin and elongated face, pointed chin and large nose. Clinical features typical of Turner syndrome are not present. A mosaic karyotype was determined by classical and molecular cytogenetic analyses. The karyotype of the patient based on fluorescent in-situ hybridization is: mos45,X[8]/46,X,idic(X)(pter→q28 q28→pter)[14]/46,XX[1].nuc ish(CEPXx1) [30/100]/ (CEPXx2)[18/100]/(CEPXx3)[52/100]. Discussion: Clinical features of the patient are presented and compared with the clinical features of the previously published cases with isodicentric X chromosome with breakpoint located at the chromosomal region Xq28. Although isodicentric X chromosome is a rare genetic disorder, it is necessary to recognize women with primary or secondary amenorrhea, growth disorder and other congenital anomalies which point to a genetic cause, by primary healtcare physicians and other specialists and refer the women to the proper medical institution for genetic testing and genetic counseling.
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