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Colobomatous Microphthalmia and Skeletal Dysplasia Syndrome via the MAB21L2 Gene

Summary and Pricing

Test Method

Exome Sequencing with CNV Detection
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
10633 MAB21L2 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
10633MAB21L281479 81479,81479 $890 Order Options and Pricing

Pricing Comments

Our favored testing approach is exome based NextGen sequencing with CNV analysis. This will allow cost effective reflexing to PGxome or other exome based tests. However, if full gene Sanger sequencing is desired for STAT turnaround time, insurance, or other reasons, please see link below for Test Code, pricing, and turnaround time information.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

Click here for costs to reflex to whole PGxome (if original test is on PGxome Sequencing backbone).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing backbone).

The Sanger Sequencing method for this test is NY State approved.

For Sanger Sequencing click here.

Turnaround Time

18 days on average for standard orders or 13 days on average for STAT orders.

Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.

EMAIL CONTACTS

Genetic Counselors

Geneticist

  • Dana Talsness, PhD

Clinical Features and Genetics

Clinical Features

Anophthalmia (A; absence of a globe in the orbit) and microphthalmia (M; reduced size of the globe) are severe and rare developmental defects of the globe with an estimated incidence of 0.2–0.4/10,000 and ~1.5/10,000 live births, respectively (Källén and Tornqvist. 2005. PubMed ID: 15971507). Both A/M may be unilateral or bilateral, and over 50% of A/M affected individuals have systemic abnormalities such as hypothalamic–pituitary disorder, mild dysmorphic facial features and short stature, urogenital anomalies, cryptorchidism and/or micropenis in males, developmental delay, seizures, oesophageal atresia or tracheoesophageal fistula and hearing loss (Ragge et al. 2005. PubMed ID: 15812812). However, only about 25% of affected individuals have distinct and well-defined syndromes (Bakrania et al. 2007. PubMed ID: 17522144). Unilateral A/M cases often have developmental anomalies of the other eye; including coloboma, lens, and optic nerve (Ragge et al. 2007. PubMed ID: 17914432).

MAB21L2-associated disorder is characterized by colobomatous microphthalmia, a distinctive skeletal dysplasia, and intellectual disability (Horn et al. 2015. PubMed ID: 26116559).

Genetics

Pathogenic variants in MAB21L2 cause a spectrum of autosomal dominant (AD) and autosomal recessive (AR) syndromic eye malformations (Rainger et al. 2014. PubMed ID: 24906020; Deml et al. 2015. PubMed ID: 25719200). Mouse model studies suggested that Mab21l2 showed strong expression in the developing eye, pharyngeal arches, and limb bud; exact function of the protein is still unknown. However, the the MAB21L2 protein binds to single stranded RNA, and this activity was lost in all altered forms of the protein. In vitro studies suggested that induced expression of of wild-type MAB21L2 increases phospho-ERK (pERK1/2) signaling (Rainger et al. 2014. PubMed ID: 24906020).

Heterozygous pathogenic variants are possibly acting in a dominant negative manner due to their increased stability and are probably associated with the abnormal persistence of pERK1/2 signaling in MAB21L2-expressing cells. This is a plausible pathogenic mechanism for the severe AD disorder. Homozygous variants in MAB21L2 might lead to complete loss of MAB21L2 RNA binding and result in a less severe AR disorder (Rainger et al. 2014. PubMed ID: 24906020). To date, only missense variants have been documented causative for the MAB21L2-associated disorder (Human Gene Mutation Database). Of note, a homozygous MAB21L2 frameshift protein truncating variant has been reported in a rare case of syndromic scrotal agenesis (Bruel et al. 2017. PubMed ID: 27103078).

Clinical Sensitivity - Sequencing with CNV PGxome

Predicting clinical sensitivity for the MAB21L2 gene is challenging due to the limited number of MAB21L2-associated cases. Analytical sensitivity should be high because all pathogenic variants reported are detectable by sequencing.

Testing Strategy

This test provides full coverage of all coding exons of the MAB21L2 gene plus 10 bases of flanking noncoding DNA in all available transcripts along with other non-coding regions in which pathogenic variants have been identified at PreventionGenetics or reported elsewhere. We define full coverage as >20X NGS reads or Sanger sequencing. PGnome panels typically provide slightly increased coverage over the PGxome equivalent. PGnome sequencing panels have the added benefit of additional analysis and reporting of deep intronic regions (where applicable).

Dependent on the sequencing backbone selected for this testing, discounted reflex testing to any other similar backbone-based test is available (i.e., PGxome panel to whole PGxome; PGnome panel to whole PGnome).

Indications for Test

Candidates for this test are patients with colobomatous microphthalmia, a distinctive skeletal dysplasia and intellectual disability. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in MAB21L2.

Gene

Official Gene Symbol OMIM ID
MAB21L2 604357
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Microphthalmia/Coloboma and Skeletal Dysplasia Syndrome AD, AR 615877

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Citations

  • Bakrania et al. 2007. PubMed ID: 17522144
  • Bruel et al. 2017. PubMed ID: 27103078
  • Deml et al. 2015. PubMed ID: 25719200
  • Horn et al. 2015. PubMed ID: 26116559
  • Human Gene Mutation Database (Bio-base).
  • Källén and Tornqvist. 2005. PubMed ID: 15971507
  • Ragge et al. 2005. PubMed ID: 15812812
  • Ragge et al. 2007. PubMed ID: 17914432
  • Rainger et al. 2014. PubMed ID: 24906020

Ordering/Specimens

Ordering Options

We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.

myPrevent - Online Ordering

  • The test can be added to your online orders in the Summary and Pricing section.
  • Once the test has been added log in to myPrevent to fill out an online requisition form.
  • PGnome sequencing panels can be ordered via the myPrevent portal only at this time.

Requisition Form

  • A completed requisition form must accompany all specimens.
  • Billing information along with specimen and shipping instructions are within the requisition form.
  • All testing must be ordered by a qualified healthcare provider.

For Requisition Forms, visit our Forms page


Specimen Types

Specimen Requirements and Shipping Details

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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ORDER OPTIONS

View Ordering Instructions

1) Select Test Method (Backbone)


1) Select Test Type


2) Select Additional Test Options

STAT and Prenatal Test Options are not available with Patient Plus.

No Additional Test Options are available for this test.

Note: acceptable specimen types are whole blood and DNA from whole blood only.
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