# Handbook of Genetic Counseling/Partial Trisomy 11q (q14-q21)

Partial Trisomy 11q (q14-q21)

## Introduction

* Introduce myself and others
* Assess concerns and what they hope to gain from the session
* Discuss reason for follow-up
* Provide overview of session

## Elicit interim medical history

* Any illnesses/hospitalizations/surgeries since last visit in September?
* Current medications
* Any recent medical tests or procedures (since September)?
* Immunizations up to date?
* Review of systems

## Elicit interim family history

* Any newborns in the family?
* Any new information about health problems in family members?
* Any significant changes in family members' health?

## Psychosocial update?

* Any changes in work?
* Who takes care of during the day?
* Any plans for more children?
* How are finances after paying for ____'s medical needs? Any assistance used or needed?

## Genetic etiology

* Partial trisomies are usually de novo
* Possible mechanisms for formation of a partial trisomy/duplucation:
* Unequal crossing over during homologous chromosome recombination in meiosis, chromosomes mispaired resulting in duplication in one set of homologous chromosomes and deletion in one set of homologous chromosomes
* Parental gonadal mosaicism-One of his parents could have duplication of this region in some germ cells (caused by same mechanism as above)
* Recurrence risk for parents to have another child with Patient's chromosome rearrangement is less than 0.5% (probably MUCH less, but in case of gonadal mosaicism, we should say this number)
* Risk for any chromosome abnormality in future pregnancy: 1/417 at age 29, 1/384 at age 30 (from Maternal-Fetal Medicine)
* Risk for Patient to have a child with the same chromosome abnormality is about 50%
* Homologous chromosome pairing during meiosis requires the chromosomes to contort in order to pair up properly-this can lead to problems during crossing over, where further chromosome abnormalities could occur, as well as formation of an extra abnormal chromosome
* Fertility may be a problem with Patient, as it commonly is in people with chromosome abnormalities (especially males) and so this may be something the parents or Patient will want to assess after puberty

## Molecular genetics

* People with duplications in different regions of 11q have been identified in the literature, but none with the same region as Patient
* Even though some of these people's duplicated regions may overlap slightly with Patient's duplicated region, there are very different genes duplicated in those people, and so we would not expect Patient to have the same effects
* Some of the documented literature:
* Delobel B, Delannoy V, Pini G, Zapella M, Tardieu M, Vallee L, Croquette MF. Identification and molecular characterization of a small 11q23.3 de novo duplication in a patient with Rett syndrome manifestations. Am J Med Genet. 1998 Nov 16;80(3):273-80.
* de Die-Smulders CE, Engelen JJ. 11Q duplication in a patient with Pitt-Rogers-Danks phenotype. Am J Med Genet. 1996 Dec 2;66(1):116-7.
* Legius E, Wlodarska I, Selleri L, Evans GA, Wu R, Smet G, Fryns JP. De novo 46,XX, dir dup (11)(q133.3-->q14.2) in a patient with mental retardation, congenital cardiopathy and thrombopenia. Clin Genet. 1996 Apr;49(4):206-10.
* Lakshminarayana P, Suresh S, Suresh I, Sriram U, Jabeen G. Inherited 11q partial trisomy. Indian J Pediatr. 1995 Mar-Apr;62(2):247-50.
* Multiple citations noting duplications of 11q in association with leukemias and lymphomas
* Bader PI, Haney SM, Munsick RA, Schubert SR, Hodes ME. Brief clinical report: neural tube defects in dup(11q). Am J Med Genet. 1984 Sep;19(1):5-8.

## Testing options

* Chromosome analysis can detect MOST duplications and other chromosome anomalies (FISH may be required if abnormal region on chromosome is small)

## Support groups

* Unique The Rare Chromosome Disorder Support Group
    http://www.rarechromo.org
    P.O.Box 2189, Caterham Surrey CR3 5GN England
    Telephone: 44 (0)1883 330766
    E-mail: info@rarechromo.org
    Web site: www.rarechromo.org
    UK-based parent resource site for information on rare chromosome disorders.
    More information-based than support-based, but has a discussion board and
appears to be up-to-date. "Little Yellow Book" is a great reference for parents available as a free pdf file. Good info on genes, chromosomes, and chromosome abnormalities.
* Chromosome Deletion Outreach (CDO)
    http://web.archive.org/19981203003403/members.aol.com/cdousa/cdo.htm
    P.O. Box 724, Boca Raton, FL 33429-0724
    Phone: 888.236.6880 (toll free)
    E-mail: info@chromodisorder.org
    Web site: www.chromodisorder .org
    This site is a resource for parents of children with rare chromosome abnormalities.
    It provides parents with contact information for people who know about specific
rare chromosome abnormalities. No one with Patient's specific duplication is listed; however, there may still be good resources for information and support.

## Conclusion/future plans

* How do you feel about Patient's health right now?
* What do you envision when you think about Patient's future?
* How do you feel about your risk for a child with a chromosome abnormality in future pregnancies?
* How do you feel about Patient's reproductive possibilities?

## Resources

* Gardner and Sutherland. Chromosome Abnormalities and Genetic Counseling. 1989.
* Thompson and Thompson. Genetics in Medicine. (5th ed.) 1991.

## Notes

The information in this outline was last updated in 3/2003.