XLMR 21: IL1RAPL1 Gene Deletion/Duplication

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Condition Description

Both deletions and point mutations in the IL1RAPL1 gene (Xp22.1-p21.3) have been associated with X-linked mental retardation (XLMR). Affected males usually have mild to severe nonsyndromic XLMR without other abnormalities, dysmorphic features, or neurological findings. Hyperactivity and self-aggressive behavior have been reported. Females in some families have been reported to have MR, while females in other families appear to be unaffected.

IL1RAPL1 may also be deleted in families with a contiguous gene deletion syndrome that includes MR, adrenal hypoplasia, Duchenne muscular dystrophy, and glycerol kinase deficiency.

For patients with suspected XLMR 21, sequence analysis is recommended as the first step in mutation identification. For patients in whom mutations are not identified by full gene sequencing, deletion/duplication analysis is appropriate.

References:

  • Carrie et al. 1999. A new member of the IL-1 receptor family highly expressed in hippocampus and involved in X-linked mental retardation. Nature Genetics 23:25-31.
  • Nawara et al. 2008. Novel mutation of IL1RAPL1 gene in a nonspecific X-linked mental retardation (MRX) family. Am J Med Genet Part A 146A:3167-3172.
  • OMIM: http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=300143

Genes (1)

Indications

This test is indicated for:

  • Confirmation of a clinical diagnosis of XLMR 21 in individuals who have tested negative for sequence analysis
  • Carrier testing in adult females with a family history of XLMR 21 who have tested negative for sequence analysis

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.

Please note that a "backbone" of probes across the entire genome are included on the array for analytical and quality control purposes. Rarely, off-target copy number variants causative of disease may be identified that may or may not be related to the patient's phenotype. Only known pathogenic off-target copy number variants will be reported. Off-target copy number variants of unknown clinical significance will not be reported.

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

Submit only 1 of the following specimen types

Preferred specimen type: Whole Blood

Type: Whole Blood

Specimen Requirements:

In EDTA (purple top) or ACD (yellow top) tube:
Infants (<2 years): 2-3 ml
Children (>2 years): 3-5 ml
Older Children & Adults: 5-10 ml

Specimen Collection and Shipping: Refrigerate until time of shipment. Ship sample within 5 days of collection at room temperature with overnight delivery.

Type: Saliva

Specimen Requirements:

OrageneTM Saliva Collection kit (available through EGL) used according to manufacturer instructions.

Specimen Collection and Shipping: Store sample at room temperature. Ship sample within 5 days of collection at room temperature with overnight delivery.

Special Instructions

Submit copies of diagnostic biochemical test results with the sample, if appropriate. Contact the laboratory if further information is needed.

Sequence analysis is required before deletion/duplication analysis by targeted CGH array. If sequencing is performed outside of Emory Genetics Laboratory, please submit a copy of the sequencing report with the test requisition.

  • Sequence analysis of the IL1RAPL1 gene is available.
  • Prenatal testing is available to couples 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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