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Microcephaly (NGS Panel and Copy Number Analysis)

CPT: 81175, 81216, 81167, 81302, 81304, 81307, 81403 (x3), 81404 (x9), 81405 (x16), 81406 (x16), 81407 (x7), 81408 (x1), 81479 (x1)

Genes Assessed


      Specimen Requirements


      Specimen

      Blood | Extracted DNA | Cultured Fibroblasts | Muscle | Buccal Cells


      Volume

      Blood: Draw blood in a lavender top EDTA tube, Sample Stability: 5-7 days, Preferred volume: 4 ml, Minimum volume: 2 ml, DO NOT FREEZE. Extracted DNA: From leukocytes, muscle, or fibroblasts: Preferred quantity: 1 microgram, Minimum quantity: 800 nanograms. Genomic DNA should be eluted in sterile Dnase/Rnase free water or TE. The A260:A280 ratio should be 1.8-2.0. Cultured Fibroblasts: Two T-25 flasks of fibroblasts, preferably ~90% confluent. TAT will be extended by 7-14 days if cells are not confluent upon arrival. Muscle: 50-75 milligrams muscle snap frozen in liquid nitrogen and maintained at -80°Celsius or below. Buccal Cells: One buccal swab should be used for collection. Do not discard solution in collection tube. Follow collection instructions supplied. Stability at ambient temperature is 60 days.


      Container

      Blood: Lavender-Top (EDTA) Tube, Buccal Swab from MNG Kit, Tissue or Extracted DNA: Sterile screw capped vial, Cultured cells: T25 flask


      Collection

      Blood: Specimens should be shipped overnight in a secure container at room temperature. Extracted DNA: Should be shipped overnight at room temperature. If previously frozen, DNA can be shipped in an insulated container with wet or dry ice. Cultured Fibroblasts: T-25 flasks containing fibroblasts should be shipped in an insulated container at room temperature. Flasks should be completely filled with media and cells should be ~90% confluent. Fibroblast samples must be certified free from Mycoplasma. MNG is able to perform this service for a small charge (TC05). For NGS panels, TAT will be extended by 7-14 days if cells are not confluent upon arrival. Muscle: Samples should be shipped frozen in an insulated container with 5-7 lbs. dry ice, overnight. Buccal cells: Should be shipped overnight in a secure container at room temperature.


      Storage Instructions

      Blood - ship ASAP, but stable up to 5 days post-collection at room temperature. DO NOT FREEZE; Swab - 60 day post-collection room temperature stability; DNA - ship at room temperature after extraction; Fibroblasts - ship flask in insulated container at room temp or refigerated; Muscle - ship in insulated container with 5-7 lbs of dry ice


      Stability Requirements

      Room Temperature: Blood - 5 days, Swab - 60 days, DNA - 30 days, Muscle - 0 days, Fibroblasts - 2-3 days; Refrigerated: Blood - 5 days, Swab - 60 days, DNA - 30 days, Muscle - 0 days, Fibroblasts - 2-3 days; Frozen: Blood - DO NOT FREEZE, Swab - 60 days, DNA - Indefinitely, Muscle - Indefinitely, Fibroblasts - Indefinitely; Freeze/Thaw: None


      Causes for Rejection

      Extracted DNA A260:A280 ratio of outside of 1.8-2.0 range; Frozen blood EDTA tube; Thawed and/or fatty muscle sample; Insufficient buccal cell collection


      Test Details


      Use

      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. Individuals with primary microcephaly have inadequate brain growth during pregnancy, and are born with a significantly small head size (OFC of < 3 SD). They may also develop mild to severe intellectual disabilities, seizures, mild short stature, and a narrow sloping forehead due to the reduced cranial size. Secondary microcephaly is observed in some metabolic disorders or genetic syndromes, such as Rett or Angelman syndromes, in which a progressive reduction in head circumference is seen in infancy or early childhood. Congenital and postnatal microcephaly can present as an isolated finding in an individual, be associated with other brain malformations such as cerebellar hypoplasia, or be part of an underlying syndrome. Syndromic microcephaly can be caused by chromosomal abnormalities, inborn errors of metabolism, single gene disorders, trauma and infection. The inheritance patterns can be autosomal dominant, autosomal recessive or x-linked.


      Methodology

      Next-Generation Sequencing


      Recommended MNG Kits

      SINGLE Blood Genetic Testing, Buccal Swab Genetic Testing