Molecular Test Listing

Molecular Requisition

Rett syndrome (RTT) is a progressive neurological disorder that affects 1 in 10,000-15,000 females, and may very rarely affect males. RTT primarily affects females, after 6-18 months of normal development. The girls then enter a short period of developmental stability before rapidly losing speech and purposeful hand movement. They develop decreased head growth resulting in microcephaly, seizures, ataxia, repetitive hand movement, screaming and crying episodes.

Rett syndrome has been found to be a result of mutations in the gene encoding the methyl-CpG-binding protein 2 (MECP2) located at Xq28. The protein acts to bind methylated CpG islands and recruits histone deacetylases and the Sin3A-histone co-repressor. The resulting protein complex induces core histone deacetylation and results in transcriptional silencing of genes.  Inheritance is X-linked dominant. However, most of the mutations are spontaneous in the affected child, and are from the paternally derived gene. Apparently asymptomatic mothers can also pass on a mutant gene, as a result of mosaicism or skewed X chromosome inactivation. There are also reports of males that survive into the newborn period but die from a severe neonatal encephalopathy.

• Girls exhibiting regression of speech and coordinated hand movement after 6-18 months of normal development.
• Girls with microcephaly, seizures, and repetitive hand movements.
• Boys with unexplained severe encephalopathy at birth.
• Children of either sex which have mental retardation, but have a normal Fragile X gene test result. 

• PCR amplification of the coding exons of the MECP2 gene and DNA sequencing.

• Blood EDTA (purple top) tubes:  

            Newborn: minimum 1-2 mL          

            Child/Adult: prefer 2 tubes of 3-5 mL

• Prenatal testing: Please contact the laboratory for instructions.

TURNAROUND TIME:     3 weeks

CPT CODES: