Microcephaly


Related Gene(s): ACTB, ACTG1, ARFGEF2, ASPM, ARX, ATR, ATRIP, CASC5, CASK, CDKL5, CDON, CENPJ, CEP135, CEP152, CEP63, CREBBP, DCX, DISP1, DHCR7, DLL1, DYNC1H1, ERCC6, ERCC8, EP300, FGF8, FKRP, FKTN, FOXG1, FOXH1, GAS1, GLI2, GPR56, HDAC8, KIF2A, KIF11, LARGE, MCPH1, MECP2, MED17, MRE11A, NBN, NDE1, NHEJ1, NIN, NIPBL, NODAL, PAFAH1B1, PCNT, PHGDH, PNKP, POMGNT1, POMT1, POMT2, PTCH1, RAB18, RAB3GAP1, RAB3GAP2, RAD21, RBBP8, RELN, RNU4ATAC, SHH, SIX3, SLC9A6, SLC25A19, SMC1A, SMC3, STAMBP, STIL, TDGF1, TGIF1, TUBA1A, TUBG1, UBE3A, VLDLR, WDR62, ZIC2

Microcephaly, holoprosencephaly, and lissencephaly are genetically heterogeneous developmental syndromes caused by germline mutations in genes involved in cell proliferation, neuronal migration, and postmigrational cortical development pathways. The general incidence of microcephaly at birth varies from 1.3 to 150 per 100,000 live births, depending on the population and the applied standard deviation threshold to define microcephaly. Performing genetic testing can be clinically useful as congenital and postnatal microcephaly could present as an isolated finding in an individual, be associated with other brain malformations such as cerebellar hypoplasia, or present as part of an underlying syndrome.

Technological and analytical test sensitivity of next generation sequencing is 99% for detecting substitutions and 95% for detecting small insertions and deletions. Larger genomic rearrangements and DNA insertions or deletions will likely be missed by this testing method. Untranslated regions (UTRs) and gene promoter regions are generally not tested. Patients with negative test results may still have a mutation in one of the genes on the panel that was not identified by this testing or may have a mutation(s) in a gene not included in this panel.


Specimen Requirements

Prenatal

  • Testing requires prior documentation of parental mutations.
  • Chorionic villi: 4 mg in conical tube with sterile saline or transport media
  • Amniotic fluid: 15 mL in conical tube
  • Cultured cells: Two confluent T-25 flasks

  • Additionally, please send:
  • Maternal blood: 5-10 mL in EDTA tube (lavender top) required to perform MCC studies on all prenatal samples and in case maternal confirmation studies are necessary
  • Paternal blood: 5-10 mL in EDTA tube (lavender top) in case paternal confirmation studies are necessary

Postnatal

  • For adults
  • Blood: Two 5-10 mL tubes with EDTA (lavender top) or two 5-10 mL tubes with ACD (yellow top) from patient
  • Additionally, please send 10-15 mL in EDTA tube (lavender top) or 10-15 mL in ACD tube (yellow top) from both parents

  • For newborns or children
  • Blood: 2 mL in pediatric EDTA tube (lavender top) or 2 mL in pediatric ACD tube (yellow top) from patient
  • Additionally, please send 10-15 mL in EDTA tube (lavender top) or 10-15 mL in ACD tube (yellow top) from both parents


Ordering Information

Shipping

  • Ship at room temperature

Turnaround Time

  • Prenatal: 3-4 weeks
  • Postnatal: 4-6 weeks


Resources

Prenatal Test Requisition with Natera NIPT
Prenatal Test Requisition with Sequenom NIPT
General Test Requisition