What Are Related Disorders?
Currently, approximately 25% of SOFT's family membership consists of parents whose child does not (or did not) have full trisomy 18 or 13. Mosaicism, partial trisomy, translocations and other related chromosomal disorders are variable phenotypes of a full trisomy. Full trisomy refers to three copies of a chromosome being present in all cells. Mosaic trisomy refers to two cell lines in a person; one with trisomy (3 copies of a chromosome), the other with 2 copies. Partial trisomy occurs when only a piece of a chromosome is extra in a person's cells due to translocation (the attachment of part of one chromosome to another).
In trisomy 13, translocation and mosaicism occur in about 20% of cases (Carey, Trisomy 13 Facts (2015) www.trisomy.org ). In trisomy 18, less than 5% have mosaicism and about 2% partial trisomy (Cereda and Carey. 2012, The Trisomy 18 Syndrome). A variable phenotype results in a wider range of outcomes; generally more optimistic, though some might be as affected as a child with a full trisomy. Retesting for mosaicism is sometimes suggested for a child with a full trisomy diagnosis, who is doing better than predicted. Survival statistics for full trisomy are generally not applicable to variable phenotypes.
Studies of groups of individuals with rare disorders are hampered by their small numbers or uniqueness, but there might be case studies for some. The NIH Genetic and Rare Disease Information Center provides information about some disorders at: https://rarediseases.info.nih.gov/. The National Organization for Rare Disorders (NORD) has a search page for rare disorders at:
Related Chromosome Disorder Groups:
Chromosome 3q Disorder Registry family information and support
4P- Support Group (Wolf-Hirshorn Syndrome)
Wolf-Hirshhorn Syndrome, Deletion 4P, A Guidebook for Families , Schaefer et al, 1996
Christine Kleimola, SOFT member, initiated and helped write this book.
Trisomy 9, Trisomy 9 Mosaic
(9TIPS) Trisomy 9 International Parent Support Group
9TIPS is an international support group for trisomy 9, covering all variations.
Phone: (909) 862-4470
Distal Trisomy 10q Families support group
Chromosome 22 Central
Stephanie St Pierre
Timmons, Ontario, Canada
Phone: (705) 268-3099
Smith/Lemli/Opitz Syndrome (SLOS)
Margaret and Jim Thompson
Phone: (972) 234-8788
National Organization for Rare Disorders (NORD) a 501(c)(3) organization, is a unique federation of voluntary health organizations dedicated to helping people with rare "orphan" diseases.
Office of Rare Disorders at the National Institutes of Health, at: rarediseases.info.nih.gov/
Genetic and Rare Diseases Information Center (GARD) rarediseases.info.nih.gov/GARD/
DiseaseInfoSearch, for information on specific genetic conditions, at: www.geneticalliance.org/
Support Groups for Chromosomal Conditions: Contact information for many specific disorder support groups. www.kumc.edu/gec/support/chromoso.html
The Children's Rare Disease Network, at: www.crdnetwork.org/
The Rare Blog, at: www.crdnetwork.org/blog/