Autosomal Dominant Mental Retardation 1: MBD5 Gene Deletion/Duplication

Condition Description

Talkowski et al. (2011) mapped the MBD5 gene (2q23.1) to the critical region of the 2q23.1 deletion syndrome.  Happloinsufficieny of the MBD5 gene causes Autosomal Dominant Mental Retardation syndrome type 1.  Overall, of the features evaluated in individuals with 2q23.1 deletion syndrome and MBD5-specific deletions, approximately 84% were observed in both groups.  Features associated with the haploinsufficiency of the MBD5 gene include intellectual disability, developmental delay, motor delay, significant speech impairment, craniofacial manifestations, seizures, constipation, and behavioral problems. 

For patients with suspected Autosomal Dominant Mental Retardation syndrome type 1, deletion/duplication analysis is recommended as the first step in mutation identification. For patients in whom mutations are not identified by deletion/duplication analysis, full gene sequencing is appropriate.

References:
  • OMIM #611472: MBD5 gene
  • OMIM #156200: Autosomal Dominant Mental Retardation Syndrome Type 1
  • Talkowski et al. (2011). Am J Hum Genet, 89, 551-563.

Genes (1)

Indications

This test is indicated for:
  • Confirmation of a clinical diagnosis of Autosomal Dominant Mental Retardation syndrome type 1.
  • Carrier testing in adults with a family history of Autosomal Dominant Mental Retardation syndrome type 1.

Methodology

DNA isolated from peripheral blood is hybridized to a CGH array to detect deletions and duplications. The targeted CGH array has overlapping probes which cover the entire genomic region.

Detection

Detection is limited to duplications and deletions. The CGH array will not detect point or intronic mutations. Results of molecular analysis must be interpreted in the context of the patient's clinical and/or biochemical phenotype.

Specimen Requirements

Listed below are EGL's preferred sample criteria. For any questions, please call 470.378.2200 and ask to speak with a laboratory genetic counselor (eglgc@egl-eurofins.com).
Submit only 1 of the following specimen types
Whole Blood (EDTA)
WBP

Requirements
EDTA (Purple Top)
Infants and Young Children (<2 years of age): 2-3 ml
Children > 2 years of age to 10 years old: 3-5 ml
Older Children & Adults: 5-10 ml
Autopsy: 2-3 ml unclotted cord or cardiac blood
Collection and Shipping
Ship sample at room temperature for receipt at EGL within 72 hours of collection. Do not freeze.
DNA, Isolated
DNA

Requirements
Microtainer
3µg
Isolation using the Perkin Elmer™Chemagen™ Chemagen™ Automated Extraction method or Qiagen™ Puregene kit for DNA extraction is recommended.
Collection and Shipping
Refrigerate until time of shipment in 100 ng/µL in TE buffer. Ship sample at room temperature with overnight delivery.
  • Sequence analysis of the MBD5 gene is available in those individuals in whom deletion/duplication analysis is negative.  
  • Custom diagnostic mutation analysis (KM) is available to family members if mutations are identified by targeted mutation testing or sequencing analysis.
  • Prenatal testing is available only for known familial mutations to individuals who are confirmed carriers of mutations. Please contact the laboratory genetic counselor to discuss appropriate testing prior to collecting a prenatal specimen.

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