What Information Found in a Family Health Tree Indicates That a Disease Might Have a Genetic Link?
Number 478 (Reaffirmed 2020)
Committee on Genetics
This certificate reflects emerging clinical and scientific advances as of the date issued and is bailiwick to modify. The information should not be construed as dictating an sectional class of treatment or process to be followed.
Abstruse: Family unit history plays a critical role in assessing the risk of inherited medical conditions and single gene disorders. Several methods have been established to obtain family medical histories, including the family unit history questionnaire or checklist and the full-blooded. The screening tool selected should be tailored to the practice setting and patient population. It is recommended that all women receive a family history evaluation as a screening tool for inherited run a risk. Family history information should be reviewed and updated regularly, peculiarly when at that place are meaning changes to family history. Where appropriate, farther evaluation should be considered for positive responses, with referral to genetic testing and counseling as needed.
Family unit history plays a critical role in assessing the run a risk of inherited medical conditions and single gene disorders. Certain types of cancer, such as breast cancer and colon cancer, appear more frequently in some families, equally exercise some agin birth outcomes. Coronary artery disease, type 2 diabetes mellitus, depression, and thrombophilias likewise have familial tendencies. The U.S. Surgeon General's Family History Initiative was launched in 2004. The goal of this initiative is to educate both health care providers and patients about the value of collecting a family history as a screening tool and to increase its use and effectiveness in clinical care past simplifying the collection procedure and analysis of the family history 1. Over the by 20 years, the Human Genome Projection has afforded us a better understanding of the effect of genetic variation on health and disease. This has furthered research in identifying genotype–phenotype correlations and enhanced the ability to predict those at risk of developing inherited medical conditions. With increased awareness of the importance of using family unit history equally a screening tool and of the value of preventive measures and increased surveillance, there is hope for improved outcomes.
Tools for Collecting the Family History
Several methods have been established to obtain family medical histories, each with its own advantages and disadvantages. A common tool used in full general do is the family unit history questionnaire or checklist. Having the patient complete the questionnaire at home allows extra time for the patient to contact family members and provide more authentic information. Direct patient questioning permits description of medical terminology that may be unclear to the patient. Any positive responses on the questionnaire should be followed up by the health care provider to obtain more than detail, including the relationship of the affected family unit member(s) to the patient, exact diagnosis, historic period of onset, and severity of disease 2.
Another family history assessment tool, commonly used by genetics professionals, is the pedigree. The health care provider may decide to complete a detailed pedigree or refer the patient to a genetics professional for farther evaluation. A full-blooded ideally shows at least three generations and involves the utilise of standardized symbols, which conspicuously mark individuals affected with a specific diagnosis to allow for easy identification Figure ane. The pedigree may visibly assistance in determining the size of the family and the mode of inheritance of a specific condition, and information technology may facilitate identification of members at increased chance of developing the condition Box 1. A pedigree should indicate the age of individuals; if deceased, the age and cause of death; and any relevant health history, illnesses, and historic period of onset. If any genetic testing has been performed on family members, the results should be indicated on the full-blooded. The ethnic background of each grandparent should be listed as well every bit whatsoever known consanguinity 3. A general inquiry about the more distant relatives should exist made in case in that location is a possible 10-linked disorder or autosomal ascendant disorder with reduced penetrance 4.
Case of a nonconsanguineous pedigree demonstrating a familial tendency for type 2 diabetes. Abbreviations: d, deceased; dx, diagnosed; P, pregnant; y.o., years ole.
Red Flags for Genetic Conditions
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Family history of a known or suspected genetic condition
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Ethnic predisposition to sure genetic disorders
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Consanguinity (blood relationship of parents)
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Multiple affected family members with the same or related disorders
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Before than expected age of onset of disease
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Diagnosis in less-oft-affected sex
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Multifocal or bilateral occurrence of illness (often cancer) in paired organs
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Illness in the absence of risk factors or later application of preventive measures
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One or more major malformations
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Developmental delays or mental retardation
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Abnormalities in growth (growth restriction, asymmetric growth, or excessive growth)
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Recurrent pregnancy losses (two or more)
Modified from the National Coalition for Health Professional Education in Genetics (NCHPEG). Genetic Red Flags: Quick Tips for Risk Assessment. Bachelor online at: http://www.nchpeg.org/. Retrieved on September iii, 2010.
The screening tool selected should be tailored to the practice setting and patient population, taking into consideration patient education level and cultural competence. Whether the pedigree or questionnaire is used, information technology is important to review and update the family history periodically for new diagnoses within the family and throughout pregnancy as appropriate. A family history screening tool will permit the health care provider to stratify levels of risk v. Moreover, the apply of a family history screening tool (full-blooded or questionnaire) has been shown to increase the likelihood of detecting a patient at high adventure of developing an inherited medical condition by 20% compared with medical tape review alone 7.
Reproductive Planning: The Preconception Menstruum
Women often discuss their pregnancy plans with their obstetrician–gynecologist before conception. The preconception period is an ideal time to provide personalized recommendations based on family unit history. The preconception consultation is also an optimal fourth dimension to review family history and discuss with a couple the option of undergoing carrier screening for genetic conditions. It is also an opportunity to address any medication concerns before pregnancy (eg, the importance of taking a folic acid supplement and fugitive medications such as angiotensin-converting enzyme inhibitors) and to ensure that medical atmospheric condition are existence advisedly evaluated. It is important to obtain the family and medical history of both the patient and her partner, including their indigenous backgrounds, any adverse pregnancy outcomes equally a couple or with other partners, and any known causes of infertility if applicable. Positive responses will need to be followed up by functioning of appropriate chance assessment, testing, and genetic counseling if needed.
Any genetic counseling and testing that can be completed earlier conception is beneficial to the couple, allowing a broader array of options and more time for decision making. Couples may decide not to excogitate, or they may consider using a gamete donor or obtaining a preimplantation genetic diagnosis if bachelor.
A patient who has had a past adverse pregnancy event or has a family history of other adverse pregnancy outcomes, such every bit miscarriage, preterm birth, a newborn screening test effect indicating an abnormality, or nativity defects, might be at increased risk of these disorders. Because both genetic and environmental factors may contribute to these outcomes, advising a patient that she is at increased risk of an agin pregnancy consequence based on family history might motivate her to reduce her environmental risk past, for instance, stopping smoking or achieving a good for you weight 8.
Common Diseases of Adult Onset and Significance of Family History
Many common adult-onset disorders demonstrate familial tendencies. However, these disorders often accept complex genetic–environmental interactions for which environmental modifications can improve the outcome or delay the onset of symptoms 5. For example, diet changes, weight loss, practice, and glucose monitoring may ameliorate the effect for an individual with a family history of type 2 diabetes mellitus. Similarly, individuals at risk of cardiovascular disease can do good from environmental modifications, such every bit achieving normal blood pressure and cholesterol levels, and those at risk of osteoporosis can undertake calcium supplementation, weight bearing exercise, and bone density screening to improve their long-term bone health.
Some family unit histories show obvious evidence of cancer risk, such as a family in which there are several members with early-onset breast cancer or colon cancer. In assessing family history of cancer risk, it is important to bank check for evidence of cancer that might be linked to a single underlying genetic crusade, such as Lynch syndrome, in which colon, endometrial, ovarian, urinary, or gastrointestinal cancer may be associated with a single familial factor mutation.
The pedigree in Figure 1 demonstrates a clear familial tendency for type 2 diabetes. The proband, or patient noted in generation Three-6, is at increased gamble of developing type 2 diabetes not only because of her family history of the disease only also considering of her development of gestational diabetes in her previous pregnancy. This patient should be counseled not merely most maintaining an advisable nutrition and exercise routine to lower her risk simply also nearly obtaining an earlier glucose screening in her current pregnancy.
Limitations
Adoption and express family size might trigger a lower threshold in detecting family history.
Recommendations
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All women should have a family history evaluation equally a screening tool for inherited take a chance.
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Family history information should be reviewed and updated regularly, peculiarly when at that place are meaning changes to family history.
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Where advisable, further evaluation should be considered for positive responses, with referral to genetic services as needed.
Copyright March 2011 by the American College of Obstetricians and Gynecologists, 409 12th Street, SW, PO Box 96920, Washington, DC 20090-6920. All rights reserved. No part of this publication may exist reproduced, stored in a retrieval system, posted on the Internet, or transmitted, in any form or past any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written per-mission from the publisher. Requests for say-so to make photocopies should exist directed to: Copyright Clearance Center, 222 Rosewood Bulldoze, Danvers, MA 01923, (978) 750-8400.
ISSN 1074-861X
Family unit history as a chance cess tool. Committee Opinion No. 478. American College of Obstetricians and Gynecologists. Obstet Gynecol 2011;117:747–fifty.
Source: https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2011/03/family-history-as-a-risk-assessment-tool
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