Alexander Disease

Alexander disease (AD) is a progressive disorder of the white matter of the central nervous system (CNS). The three types of AD are categorized by age of onset: infantile, juvenile, and adult. Affected infants develop a megalencephalic leukodystrophy, seizures, spasticity, ataxia, and psychomotor retardation. Infantile AD frequently leads to death within a decade after the diagnosis. Juvenile and adult forms of AD have a more slowly progressive course and are characterized by ataxia, bulbar signs and spasticity. Rosenthal fibers, observed in the astrocytes of affected individuals upon autopsy, are a hallmark feature of AD. These cytoplasmic inclusions are made up of glial acidic fibrillary protein (GFAP) and small heat-shock proteins. MRI has proven to be a useful tool for diagnosing AD, and often shows high signal intensity of white matter in the frontal area and basal ganglia. Alexander disease is usually sporadic and is most often caused by de novo heterozygous mutations in the GFAP gene. The recurrence risk, even when both parents are negative for GFAP mutations, is unknown and may thus warrant consideration of prenatal diagnosis for couples who have had an affected child. There is one report of a clinically-diagnosed Alexander disease patient with apparent autosomal recessive mutations in the NDUFV1 gene.

Tests Available

Forms and Documents

Test Details

GFAP
  • Confirmation of a clinical diagnosis
  • Differentiation of Alexander disease from Canavan disease
  • Prenatal diagnosis in at-risk pregnancies
  • Capillary Sequencing

Ordering

218
3 weeks
2-5 mL Blood - Lavender Top Tube
Oral Rinse (30-40 mL) | Dried Blood Spots | Buccal Swabs

Billing

81405x1
No
Yes
  • 330 Cerebral degenerations usually manifest in childhood Use additional code to identify associated mental retardation
  • 742.4 Other specified anomalies of brain, Congenital cerebral cyst, Macroencephaly, Macrogyria, Megalencephaly, Multiple anomalies of brain NOS, Porencephaly Ulegyria
  • 330.8 Other specified cerebral degenerations in childhood, Alpers' disease or gray-matter degeneration, Infantile necrotizing encephalomyelopathy, Leigh's disease, Subacute necrotizing, encephalopathy or encephalomyelopathy
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References

  1. Schuelke, M et al., Mutant NDUFV1 subunit of mitochondrial complex I causes leukodystrophy and myoclonic epilepsy. Nat Genet 21(3):260-1. 1999
  2. Brenner, M et al., Mutations in GFAP, encoding glial fibrillary acidic protein, are associated with Alexander disease Nature Genetics 27:117-120 (2001)
  3. Meins M et al., Infantile Alexander Disease: A GFAP Mutation in Monozygotic Twins and Novel Mutations in Two Other Patients Neuropediatrics 33:194-198 (2002)
  4. Rodriguez D et al., Infantile Alexander Disease: Spectrum of GFAP Mutations and Genotype-Phenotype Correlation Am J Hum Genet 69:1134-1140 (2001)
  5. Gorospe JR et al., Molecular findings in symptomatic and pre-symptomatic Alexander disease patients Neurology 58: 1494-1500 (2002)

Forms and Documents

Test Details

AARS, AARS2, ABAT, ABCD1, ACADS, ACER3, ACOX1, ACY1, ADAR, ADGRG1, ADSL, AHDC1, AIMP1, ALDH3A2, ALDH6A1, AMN, AMPD2, ANK3, AP4B1, AP4S1, APOPT1, ARHGAP31, ARHGEF10, ARNT2, ARSA, ASNS, ASPA, ASXL1, AUH, BCAP31, BCS1L, BEST1, BMP4, BRAT1, CARS2, CCDC88A, CHMP2B, CLCN2, CLN6, CLP1, COL4A1, COL4A2, COX10, COX15, COX7B, CPLX1, CSF1R, CTBP1, CTC1, CTDP1, CYP27A1, CYP7B1, D2HGDH, DAG1, DARS, DARS2, DDHD2, DEAF1, DHFR, DHH, DLL4, DNM2, DOCK6, DPYS, DYRK1A, EARS2, EDNRB, EGR2, EIF2B1, EIF2B2, EIF2B3, EIF2B4, EIF2B5, ENTPD1, EOGT, ERCC2, ERCC6, ERCC8, FA2H, FAM126A, FBXL4, FGD4, FGFRL1, FIG4, FKRP, FOXC1, FOXG1, FOXRED1, GAA, GALC, GAN, GBE1, GCDH, GDAP1, GFAP, GFM1 (EFG1), GJA1, GJB1, GJC2, GLB1, GLUL, GLYCTK, GNAO1, GRM7, GRN, HEPACAM, HEXA, HSD17B4, HSPD1, HTRA1, IBA57, IDUA, IER3IP1, IFIH1, ISCA2, ITPA, KARS, KCNJ10, KCNT1, L2HGDH, LAMA1, LAMA2, LAMB1, LARGE1, LETM1, LIPT1, LITAF, LMNB1, LRPPRC, LYRM7, MAPT, MARS2, MAT1A, MCOLN1, MEF2C, MLC1, MOCS1, MOCS2, MPV17, MPZ, MRPS22, MTFMT, MTTP, MUT, NADK2, NDRG1, NDUFA1, NDUFA10, NDUFA11, NDUFA12, NDUFA2, NDUFA9, NDUFAF2, NDUFAF3 (C3ORF60), NDUFAF4 (C6ORF66), NDUFAF5, NDUFAF6, NDUFB3, NDUFB9, NDUFS1, NDUFS2, NDUFS3, NDUFS4, NDUFS6, NDUFS7, NDUFS8, NDUFV1, NDUFV2, NDUFV3, NEFL, NFU1, NGLY1, NOTCH1, NOTCH3, NRXN1, NSD2, NUBPL, OCRL, PAFAH1B1, PC, PCDH12, PDYN, PEX1, PEX10, PEX11B, PEX12, PEX13, PEX14, PEX16, PEX19, PEX2, PEX26, PEX3, PEX5, PEX6, PEX7, PGAP1, PHGDH, PHYH, PIGA, PLEKHG2, PLP1, PMP22, POLG, POLR1C, POLR3A, POLR3B, POMK, POMT1, PPP2R1A, PRKDC, PRPS1, PRX, PSAP, PSEN1, PTEN, PURA, PYCR2, QARS, RARS, RBPJ, RMND1, RNASEH2A, RNASEH2B, RNASEH2C, RNASET2, RNF216, RPIA, RPS6KC1, SAMHD1, SBF2, SCP2, SDHA, SDHAF1, SDHB, SDHD, SEPSECS, SH3TC2, SHANK3, SHPK, SLC16A2, SLC17A5 , SLC1A4, SLC25A1, SLC25A12, SLC25A22, SLC33A1, SLC35A2, SLC46A1, SLC6A8, SNIP1, SOX10, SPATA5, SPG11, SPG20, SPTAN1, SQSTM1, SSR4, STAMBP, STAT1, STXBP1, SUMF1, SURF1, SYNE1, TACO1, TAF2, TARS2, TM4SF20, TMEM126B, TMEM165, TMEM187, TMEM70, TRAPPC9, TREM2, TREX1, TRMT10A, TRMT5, TSC1, TSEN54, TUBB2A, TUBB4A, TUFM, TYMP, TYROBP, UBE2A, UPB1, VARS2, VCP, VPS11, WWOX, ZEB2, ZFYVE26, ZNF335
  • Molecular confirmation of a clinical diagnosis
  • To assist with decisions about treatment and management of individuals with leukodystrophy or leukoencephalopathy
  • Testing of at-risk relatives for specific known variant(s) previously identified in an affected family member
  • Prenatal diagnosis for known familial pathogenic variant(s) in at-risk pregnancies
  • Next-Gen Sequencing

Ordering

J853
6 weeks
2-5 mL Blood - Lavender Top Tube
Oral Rinse (30-40 mL) | Buccal Swabs

Billing

81404x5, 81405x6, 81406x5, 81401x1
Yes
Yes
* For price inquiries please email zebras@genedx.com

References

  1. Vanderver A et al. Leukodystrophy Overview. 2014 Feb 6. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: https://www.ncbi.nlm.nih.gov/books/NBK184570/.
  2. Bonkowsky et al. (2010) Neurology 75 (8):718-25 (PMID: 20660364)
  3. Heim P, Claussen M, Hoffmann B, Conzelmann E, Gärtner J, Harzer K, Hunneman DH, Köhler W, Kurlemann G, Kohlschütter A. Leukodystrophy incidence in Germany. Am J Med Genet. 1997;71:475–8 (PMID: 9286459).
  4. Zou et al. Whole exome sequencing: an effective and comprehensive genetic testing approach for leukodystrophy [abstract submitted] To be presented at the 2017 ASHG Annual Genetics Meeting, October 17-21, Orlando, FL.