Microcephaly

Microcephaly is defined as a small cranium with an occipito-frontal head circumference (OFC) of more than two standard deviations (SD) below the mean for age, sex, and ethnicity. Microcephaly can be congenital (primary microcephaly) or develop postnatally (secondary microcephaly). Either type can be caused by environmental or genetic factors. Approximately 15-50% of individuals with microcephaly have been reported to have an underlying genetic etiology. Individuals with primary microcephaly have inadequate brain growth during pregnancy, and are born with a significantly small head size (OFC of < 3 SDs). They may also develop mild to severe intellectual disabilities, seizures, mild short stature, and a narrow sloping forehead due to the reduced cranial size. Imaging typically reveals a normal brain structure with reduction in size, particularly of the cerebral cortex. The brain size in cases of secondary microcephaly has the expected size at birth but subsequently fails to grow normally. Common causes of secondary microcephaly include environmental insults, such as infections or a brain injury. In addition, secondary microcephaly is observed in some metabolic disorders or genetic syndromes, such as Rett syndrome and Angelman syndrome, in which a progressive reduction in head circumference is seen in infancy or early childhood.Congenital and postnatal microcephaly could present as an isolated finding in an individual, be associated with other brain malformations such as cerebellar hypoplasia, or as part of an underlying syndrome.

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AMPD2, ANKLE2, AP4M1, ARFGEF2, ASPM, ASXL1, ATR, ATRX, BRAT1, CASK, CDK5RAP2, CDKL5, CENPE, CENPF, CENPJ, CEP135, CEP152, CIT, CREBBP, CTNNB1, DDX3X, DHCR7, DIAPH1, DYRK1A, EFTUD2, EP300, FOXG1, IER3IP1, KAT6A, KATNB1, KIF11, KIF1A, KMT2D, KNL1, MCPH1, MECP2, MED17, MYCN, NIPBL, PCNT, PNKP, RAB18, RAB3GAP1, RAB3GAP2, RBBP8, RNASEH2C, RTTN, SEPSECS, SLC25A19, SLC9A6, SNAP29, STAMBP, STIL, TCF4, TRAPPC9, TSEN54, TUBA1A, TUBB3, TUBGCP4, TUBGCP6, UBE3A, VPS13B, WDR62, ZEB2, ZNF335
  • Molecular confirmation of a clinical diagnosis
  • Establish the type of microcephaly and cause in order to provide information regarding prognosis, management and recurrence risk.
  • Testing of at-risk relatives for specific known pathogenic variant(s) previously identified in an affected family member
  • Prenatal diagnosis for known familial pathogenic variant(s) in at-risk pregnancies
  • Next-Gen Sequencing
  • Deletion/Duplication Analysis

Ordering

689
4 weeks
2-5 mL Blood - Lavender Top Tube
Oral Rinse (30-40 mL) | Buccal Swabs

Billing

81404x1, 81405x2, 81406x2, 81407x1, 81302x1, 81304x1
Yes
Yes
* For price inquiries please email zebras@genedx.com

Forms and Documents

Test Details

  • Molecular confirmation of a clinical diagnosis
  • Establish the type of microcephaly and cause in order to provide information regarding prognosis, management and recurrence risk.
  • 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

J511
6 weeks
2-5 mL Blood - Lavender Top Tube
Oral Rinse (30-40 mL) | Buccal Swabs

Billing

81404x3, 81405x3, 81406x1, 81407x2, 81408x2
Yes
Yes
* For price inquiries please email zebras@genedx.com

References

  1. Ashwal et al., (2009) Neurology 73(11): 887-897 (PMID: 19752457).
  2. Kaindl et al., (2010) Progress in Neurobiology 90:363-383 (PMID: 19931588).
  3. Verloes A, Drunat S, Gressens P, et al. Primary Autosomal Recessive Microcephalies and Seckel Syndrome Spectrum Disorders. 2009 Sep 1 [Updated 2013 Oct 31]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews [Internet]. Seattle (WA): Univers
  4. Woods CG (2004) Current Opinion in Neurobiology 14:112-117 (PMID: 15018946).
  5. Abuelo, D (2007) Semin Pediatr Neurol 14:118-127 (PMID: 17980308).
  6. Faheem et al., (2015) BMC Med Genomics 8 Suppl 1:S4 (PMID: 25951892).
  7. Shanmugham et al., Trio-based whole exome sequencing (WES): an effective diagnostic tool for patients with microcephaly [abstract]. In National Society of Genetic Counselors Annual Education Conference 2016 Sept 27-Oct 1, Seattle WA