Alias: Monosomy 1p36
Gene(s) involved: Deletion of genes in the 1p36 critical region.
Brief description of disorder: Clinical features of 1p36 deletion syndrome include mental retardation, poor/absent speech, hypotonia, brachycamptodactyly, short feet, brain abnormalities, congenital heart defects, eye/ vision problems, seizures, skeletal anomalies, and specific craniofacial findings.
The prevalence of 1p36 deletion syndrome is estimated as 1:5,000 to 1:10,000 births, with a 2:1 female to male ratio.
Inheritance pattern: 1p36 deletion syndrome can result from an inherited or de novo chromosome abnormality. Parents of affected individuals should undergo subtelomeric cytogenetic analysis specific for a translocation involving 1p36. Analysis of both parents is appropriate in the case of a proband with a suspected de novo deletion, as this could possibly reveal a cryptic balanced translocation involving chromosome 1 in a parent. Array CGH testing is contraindicated for this chromosomal rearrangement due to the likely presence of a balanced translocation, which is not detectable by aCGH.
Genetics: It is estimated that 52% of individuals with 1p36 deletion syndrome have a de novo terminal 1p36 deletion. 1p36 deletion syndrome can also result from an interstitial deletion (29%), complex rearrangements involving either more than one 1p36 deletion, or a 1p36 deletion with a 1p36 duplication (12%), or a derivative chromosome 1, in which the 1p telomeric region is replaced with the end of another chromosome (7%). Risks to family members are dependent upon the mechanism of origin of the deletion.
Test Method: Conventional G-banded cytogenetic analysis, FISH and array can be used to detect deletions.
Test sensitivity: Cytogenetic analysis detects approximately 25% of deletions that are greater than 5Mb. FISH and array will detect 98-100% of deletions. Deletions that are smaller than 100kb will not be detected by aCGH and deletions smaller than the FISH probe will not be detected by FISH.
Specimen requirements for Cytogenetic Analysis, FISH, or Array.
Adult: 3-5 ml peripheral blood in a sodium-heparin tube.
Newborn: 1-3 ml blood in a sodium-heparin tube.
Turn-around-time:
Newborns: 2-3 days
Non-STAT: 2-14 days
FISH: 6-8 days
Array: 5-14 days
References: GeneReviews
revised 5-21-2011
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