Chromosome 16q: Loss of Heterozygosity (LOH) refers to the loss of genetic material normally found on the short arm of one of the patient's two copies of chromosome 16. Occurs in approximately 5% of favorable (non-anaplastic) histology Wilm’s tumor (FHWT) cells and has been shown to be associated with inferior relapse-free survival (RFS) and overall survival (OS) in patients with FH Wilm’s tumor. This testing is commonly done in conjunction with Chromosome 1p: Loss of Heterozygosity (NAACCR ID: 3801) and Chromosome 1q: Loss of Heterozygosity (NAACCR ID: 1190).

This is a special molecular diagnostic test performed on tumor tissue to identify loss of genetic material found on the long arm of one of the patient’s two copies of chromosome 16. A normal cell will contain two complete copies of each chromosome, one from each parent, and this normal state is termed heterozygous. Loss of heterozygosity (LOH) is an abnormal state reflecting loss of the whole arm of chromosome 16q following a chromosomal translocation event.

This is part of the National Childhood Cancer Registry (NCCR) project to collect more specific information on pediatric patients. Registries part of the NCCR will start collection on specific pediatric data items with 2024+ diagnoses.

Source documents: molecular pathology report (may be addendum to original pathology report).

Note 1: Effective years

• This SSDI is effective for diagnosis years 2024+
• For cases diagnosed 2018-2023, this SSDI must be blank

Note 2: Physician statement

• Physician statement of Chromosome 16q deletion/LOH can be used to code this data item when no other information is available.