Fragile X


To examine carrier status of Fragile X syndrome, CGG repeat size was assessed using AmplideX FMR1 (kit#49402 Asuragen, Austin, TX). All results are reported in reference to Human Genome 19, Human Build 37.

Sample requirements

By default, Gene by Gene will provide buccal (cheek) swab kits with each order. Each test requires two buccal swabs which are included in each kit. This is the preferred sample collection method. Each kit comes with return packaging and pre-paid shipping label. *Shipping fees may apply to orders outside the United States. If necessary, Gene by Gene can accept most DNA sample types, including:

  • Extracted DNA: 20ul of 50ng/ul, OD260/OD280 ~ 1.8, include details of extraction method with samples
  • Blood: 3-5cc drawn in EDTA (purple-top) tube (additional $50 extraction fee per sample)
  • Shipping: For all non-buccal sample types, ship at room temperature in an insulated container. DO NOT HEAT OR FREEZE SAMPLE.


Genomic DNA is extracted following standard protocols. DNA is amplified to obtain coding exons and their flanking regions (approximately 50 bp on either side). Sequencing is done via Sanger-sequencing method, and all fragments are sequenced by forward and reverse internal primers when possible to determine the noted regions. When coverage with both forward and reverse primers is not possible, PCR and sequencing are performed in at least two independent reactions in one direction. Mutations are scored relative to the reference sequences deposited in the publicly available database NCBI and following the recommendations of the human genetic variation nomenclature scheme. Accordingly, exon 1 of the tested gene is defined as the exon in which the first ATG appears. Chromosomal positions are indicated according to the hg19 reference assembly. Clinical reports are reviewed and approved by the Gene by Gene Chief Medical Officer and the Clinical Laboratory Director.
Test Request Form