How to Make a Pedigree Chart of Your Family
Family History: The 3-Generation Pedigree
Am Fam Dr.. 2005 Aug one;72(three):441-448.
Related Editorial
This article exemplifies the AAFP 2005 Annual Clinical Focus on the legal, social, clinical, and ethical bug of medical genomics.
Article Sections
- Abstruse
- Function Collection of Family History
- Patient Drove of Family History
- Assessment
- When Family History Suggests a Genetic Condition
- References
The drove of a family history ranges from merely asking patients if family members have the same presenting illness to diagramming circuitous medical and psychosocial relationships as function of a family genogram. The 3-generation full-blooded provides a pictorial representation of diseases inside a family unit and is the most efficient manner to assess hereditary influences on disease. Ii recent events have made family history assessment more of import than ever: the completion of the Human Genome Project with resultant identification of the inherited causes of many diseases, and the institution of national clinical practice guidelines based on systematic reviews of preventive interventions. The family history is useful in stratifying a patient's gamble for rare unmarried-gene disorders and more mutual diseases with multiple genetic and ecology contributions. Major organizations have endorsed using standardized symbols in pedigrees to identify inherited contributions to disease.
A 3-generation pedigree has been used for diagnostic consideration or risk assessment of rare unmarried-factor or chromosomal disorders. However, the utility of family unit history in the assessment of hazard for mutual diseases is becoming increasingly recognized.1–3 Nigh common diseases result from a combination of environmental factors and variations in multiple genes. Inherited variations within these genes confer individual risks that tin can differ profoundly from the population-based average. Assessment of family history is useful to detect increased risks for diseases that have modifiable take chances factors or preventable exposures. Clinical preventive measures for asymptomatic patients recommended by the U.S. Preventive Services Task Force involve a consideration of relevant family history (Tabular array 1iv–thirteen ). Family history assessment also tin help identify relatively rare conditions that may non exist considered in a differential diagnosis (Tabular array 2). Alternatively, when a relatively common disease is acquired by an inherited mutation in a single gene, family history assessment may lead to early diagnosis and more aggressive management (Tabular array 3).
Tabular array one
USPSTF Recommendations Based on Family unit History
| Level | Topic | Recommendation | Clinical considerations |
|---|---|---|---|
| A | Aspirin for primary prevention of cardiovascularevents4 | Hash out aspirin chemoprevention with adults who are at increased risk of coronary centre disease. | Run a risk cess should include questions almost age, sex, diabetes, elevated total cholesterol levels, low loftier-density lipoprotein cholesterol levels, elevated claret pressure, family history, and smoking. |
| A | Screening for colorectal cancer5 | Screen men and women fifty years and older for colorectal cancer. | Initiating screening at an earlier age is reasonable in persons at higher take a chance (eastward.g., those with a outset-degree relative who receives a diagnosis earlier 60 years of age). |
| Expert guidelines be for screening very high-take a chance patients, including those with a history suggestive of familial polyposis or hereditary nonpolyposis colorectal cancer. | |||
| B | Behavioral counseling in primary intendance to promote a healthy diet6 | Counsel adult patients with hyperlipidemia and other known risk factors for cardiovascular and nutrition-related chronic disease. | — |
| B | Chemoprevention of chest cancer7 | Discuss chemoprevention with women at high adventure for breast cancer and at low risk for agin effects of chemoprevention. | Older age, a family history of breast cancer, and a history of atypical hyperplasia on breast biopsy are the strongest run a risk factors for breast cancer. |
| B | Screening for abdominal aortic aneurysm8 | Perform ane-fourth dimension ultrasound screening in men 65 to 75 years of age who have ever smoked. | Major gamble factors include age (65 years or older), male sex activity, and a history of smoking (at to the lowest degree 100 cigarettes in a person's lifetime). A first-degree family history of intestinal aortic aneurysm that required surgical repair also increases men's risk. |
| B | Screening for chest cancer9 | Perform screening mammography, with or without clinical breast examination, every one to two years in women xl years of age and older. | Women at increased gamble for breast cancer (east.g., those with a family history of breast cancer in a female parent or sister, a previous chest biopsy revealing singular hyperplasia, first childbirth afterward age 30) are more likely to do good from regular mammography than women at lower risk. |
| B | Screening for lipid disorders in adults10 | Screen men twenty to 35 years of age and women twenty to 45 years of age with diabetes, a family history of cardiovascular disease before historic period fifty in male relatives or age threescore in female relatives, or a family history suggestive of familial hyperlipidemia. | — |
| D | Screening for pancreatic cancer11 | Do non screen routinely for pancreatic cancer in asymptomatic adults using intestinal palpation, ultrasonography, or serologic markers. | Persons with hereditary pancreatitis may have a higher lifetime risk for developing pancreatic cancer. |
| I | Screening for prostate cancer12 | Show is insufficient to recommend for or against routine screening for prostate cancer using prostate-specific antigen testing or digital rectal test. | Men older than 45 years of age who are at increased gamble (e.g., blackness men, men with a family history of prostate cancer in a first caste relative) are most probable to benefitfrom screening. |
| I | Newborn hearing screening13 | Show is insufficient to recommend for or against routine screening of newborns for hearing loss during postpartum hospitalization. | The screening yield and proportion of true-positive results will exist substantially higher when screening is targeted at loftier-risk infants (e.thou., those admitted to the neonatal intensive care unit for 2 days or more, infants with syndromes known to include hearing loss or a family history of babyhood sensorineural hearing loss, congenital infections, and craniofacial abnormalities). |
TABLE two
Symptoms and Family History Suggestive of Single-Gene Disease
| Primary symptom | Family history | Affliction | Gene |
|---|---|---|---|
| Fatigue or arthralgias | Diabetes or cirrhosis | Hereditary hemochromatosis | HFE |
| Nonfebrile seizure | Seizures, developmental delay, mental retardation, tumors | Tuberous sclerosis | TS1, TS2 |
| Recurrent UTI or hematuria | Hypertension, nephrolithiasis, cerebral aneurysm, or renal failure | Autosomal-dominant PKD | ADPKD1, ADPKD2 |
| Shortness of jiff | Epistaxis, telangiectasias | Hereditary hemorrhagic telangiectasia | ENG, ACVRL1 |
| Shortness of breath | Heart failure (cor pulmonale) | Idiopathic pulmonary hypertension | BMPR2 |
| Syncope | Syncope, sudden death | Long QT syndrome | Multiple |
Table three
Common Diagnoses Suggestive of Single-Gene Disease
| Diagnosis | Family unit history | Disease etiology | Factor |
|---|---|---|---|
| DVT | DVT, pulmonary embolism | Hereditary thrombophilia | Multiple; F5 |
| Most common: activated protein resistance-gene V Leiden | |||
| Emphysema | Emphysema | α-one antitrypsin deficiency | SERPINA |
| Glaucoma (master open up-angle) | Glaucoma | Hereditary glaucoma | MYOC |
| Pancreatitis | Pancreatitis | Hereditary pancreatitis | PRSS1 |
Prevention efforts are enhanced by family discussions that shed light on lifestyles or family unit behaviors that accept adverse health consequences. Prevention also is achieved by identifying patients with a higher take chances than the population average because of shared inherited factors associated with disease. In some cases, standard screening may be supplanted by targeted genetic testing and a change in clinical intervention for persons at high risk for disease, such as those with a strong family history of cancer.
Office Drove of Family History
- Abstract
- Function Collection of Family unit History
- Patient Collection of Family unit History
- Cess
- When Family History Suggests a Genetic Condition
- References
Physicians tin can use several approaches to collect family information and construct a pedigree. The most traditional arroyo is doctor-directed questioning of the patient or family informant. Nurses, physician assistants, and other trained clinical staff also may consummate this process. This arroyo typically takes xv to 30 minutes. Alternatively, patients can be provided with questionnaires nearly their family history information before an part visit. This method still requires a health professional person to review the data and create a pedigree.
Unfortunately, a wellness maintenance visit does not allow for this amount of time to devote to family history drove.14 In reality, the average function visit lasts 16 minutes, and family history discussion has been observed to last less than three minutes.xv,xvi Many physicians recoup for this fourth dimension limitation past collecting family unit history data piecemeal over several visits. Checklists may be used in an attempt to speed data collection, just the usefulness of this approach may exist express by patient recall. Checklists likewise may not distinguish which relatives are afflicted or their degree of relatedness to the patient. Additionally, unknown family medical data, a patient's focus on an acute trouble, and fright of bigotry may impede collection of a consummate and accurate family history.
Patient Collection of Family History
- Abstract
- Part Collection of Family History
- Patient Collection of Family History
- Assessment
- When Family History Suggests a Genetic Condition
- References
With guidance, patients may construct their own pedigrees, which should be reviewed by the physician to assure their accuracy. The American Medical Association has adult a pocket guide that provides instructions and examples for patients on how to generate a full-blooded. Information technology is available online athttp://www.ama-assn.org/ama/pub/category/2380.html.
A impress and Web-based tool developed as part of the U.Due south. Surgeon General's Family unit History Initiative17 is available online athttp://www.hhs.gov/familyhistory. This tool, which is available in English and Spanish, guides the collection of family history, which is and then transferred to a printable, standardized, 3-generation pedigree. Specific questions target six developed diseases: heart disease; diabetes; stroke; and chest, ovarian, and colon cancers. These diseases are highlighted considering they are common and require a alter in clinical evaluation or intervention based on family history. Families are encouraged to seek specific data directly from family members, their physician, and medical records.
Assessment
- Abstract
- Office Drove of Family History
- Patient Collection of Family History
- Assessment
- When Family History Suggests a Genetic Condition
- References
Regardless of whether family history was collected in the physician'south office or the patient's domicile, assessment should occur at the initial patient evaluation and exist updated periodically to place newly diagnosed medical or developmental conditions within the family. Physicians should begin with recording the current age and historic period at onset of symptoms or diagnosis of the patient and showtime-, second-, and third-degree relatives on each side of the family unit. The historic period and crusade of death for deceased family members also should exist recorded. The accuracy of data generally decreases as the caste of relatedness decreases. Therefore, physicians should note when data is from a medical source instead of a family report.
The most useful family history includes medical, developmental, and pregnancy issue information on get-go-, second-, and third-degree relatives.18 The degree of relatedness indicates the per centum of shared genes (Tabular array 4). For example, the half-sibling and the uncle of a patient inherit the aforementioned proportion of genes (25 per centum) identical to the patient'south. Standard symbols and diagrams let rapid attribution of diseases to detail branches of the family unit ( Effigy 1 19). Having two relatives from the aforementioned side of the family affected with cancer (one with endometrial cancer and the other with colon cancer) increases suspicion for hereditary nonpolyposis colon cancer (an inherited form of colon cancer) more if i relative was from the paternal side of the family and the other from the maternal side.
TABLE 4
Shared Genes in Blood Relatives
| Outset-degree relative (fifty% shared genes) | Second-degree relative (25% shared genes) | Third-degree relative (12.5% shared genes) |
|---|---|---|
| Children | Aunts and uncles | Cousins |
| Parents | Grandparents | Great-grandparents |
| Siblings | Half siblings | |
| Nieces and nephews |
Pedigree Symbols
Figure one.
Standard pedigree symbols used in the drove of a family history.
Medical information often is non known because of generational, cultural, or wellness literacy problems. For example, older relatives mistakenly may believe that discussion of a cancer diagnosis is futile, because in the past there was not effective treatment. A couple planning to take children may not know the relevance of inquiring nearly previous miscarriages in the family unit, and family unit members may not volunteer this emotionally sensitive information. Weather that are thought to occur sporadically actually could be inherited. For example, a family history of multiple relatives with Down syndrome suggests an inherited translocation, not sporadic non-disjunction. A woman may not realize that her paternal grandmother'south and aunt's breast cancer diagnoses confer the same risk to her as if they were maternal relatives. Therefore, encouraging observation of health information for three generations of relatives is warranted.
Consanguinity, the shared relationship of a common ancestor, is frequent in many cultures and should exist considered in the evaluation of a patient with unusual symptoms or those suggestive of a rare disease. Persons from cultures within which intermarriage remains common share a greater proportion of genes. In Republic of iraq, for example, 29.2 percent of marriages are betwixt first cousins, and 57 percent of marriages demonstrate some amount of consanguinity.xx An autosomal-recessive disease is more probable to occur in a consanguineous family because of the increased probability of a person having two copies of the aforementioned mutation in a gene.21 Recurrence of mutual circuitous diseases also may exist increased in the children of consanguineous parents because of a greater proportion of shared genes.
Physicians should place patients' ancestries and, if known, the countries of origin of their grandparents. A single gene may have genetic variations whose frequencies differ depending on bequeathed origin. A low mean corpuscular volume and normal iron studies in a patient without chronic disease signals a diagnosis of thalassemia trait. If a patient and partner with these findings are sure that their ancestors were from Africa, they have a very low likelihood of having a clinically affected child. Just if the patient or partner has an antecedent from southeast Asia, in that location is an increased chance of thalassemia H or even fatal hydrops in their kid. Many diseases are more prevalent in certain ancestral groups. For example, persons of Ashkenazi Jewish or Muslim Arabic origin share odds of one in four for conveying a defective gene for familial Mediterranean fever.22 In these patients, awareness of their disease risk is of import because early diagnosis avoids prolonged evaluation for other disorders and makes constructive treatment possible.
The recall of spontaneous abortions, stillbirths, illnesses, and deaths of family members may evoke strong emotional responses in patients. Feelings of guilt and blame are not unusual in families in which several relatives are affected past the same status. Visualizing the family history in pictorial form may clarify risks to a patient that had non been appreciated previously. Establishing a relationship with a geneticist or genetic counselor may be helpful, although genetics professionals are non widely available. Extra clinic time and the assistance of mental health professionals may exist required.
Relatives sometimes may be identified who have significant risk for a disease and in whom early intervention may improve outcomes. The patient should be encouraged to notify these family members of their risk and refer them to a physician. In these cases, the physician'south obligation to warn other family members directly is not articulate.23 At that place have been successful claims of negligence against physicians for failure to warn patients that their family members were at increased gamble for colon and breast cancers.24
The exact duty of the doc in these instances ofttimes is untested, particularly given the restrictions of the Health Insurance Portability and Accountability Act, and is subject to individual state court estimation. Therefore, disclosure to other family unit members must be considered carefully with respect to privacy and weighed against a duty to warn.
When Family unit History Suggests a Genetic Condition
- Abstract
- Role Drove of Family unit History
- Patient Collection of Family History
- Assessment
- When Family unit History Suggests a Genetic Condition
- References
In some patients, the family history may exist significant enough (e.g., multiple affected relatives with early onset of a illness) to consider genetic testing for an identified or suspected mutation in a unmarried gene. If the tested cistron is a component of a complex disease, a constitute mutation offers susceptibility or predictive, but not confirmatory, information. The degree of chance owing to variations or mutations in a single gene tin range from a minor contribution in complex disease to near 100 pct certainty. For example, a variation in the APC factor found in the Ashkenazi Jewish population confers a pocket-sized risk of colorectal cancer.25 Other mutations in the same cistron cause familial adenomatous polyposis with a nigh 100 percent lifetime take chances of colorectal cancer.
Susceptibility or predictive testing for familial cancers may significantly decrease morbidity or mortality past changing the management of the disease. Alternative screening with lower specificity just higher sensitivity may be sought (east.thousand., magnetic resonance imaging for early breast cancer detection), and chemoprophylaxis may exist offered (east.thou., tamoxifen [Nolvadex] for breast cancer prevention). Aggressive screening and surgical prophylaxis may be initiated (e.g., colonoscopy for detection and removal of precancerous lesions in patients with hereditary nonpolyposis colon cancer). Early surgical intervention may be recommended as preventive measures (e.chiliad., in family members of a patient with a mutation of the MEN2A cistron who inherit a mutation in the RET gene and are virtually sure to develop medullary thyroid carcinoma) or offered (eastward.thou., mastectomy or oophorectomy may exist chosen by patients with an unidentified BRCA1/2 mutation). Predictive testing for noncancerous conditions also may be initiated. In an adult who has asthma that cannot be improved with bronchodilators, the riskof α-ane antitrypsin deficiency increases if there is a family history of emphysema or bronchiectasis. If airf low obstacle is found to be incompletely reversible on pulmonary part testing, the patient is a candidate for genetic testing.26
Family history too may guide diagnosis even when Deoxyribonucleic acid-based genetic testing is not available for an inherited status. In a child presenting with a syncopal episode, a family history of syncope prompts consideration of long QT syndrome.27 In an adult presenting with fatigue or arthralgias, a family unit history of diabetes and cirrhosis should signal measurement of transferrin saturation and consideration of hereditary hemochromatosis.28
New guidelines incorporating genomic principles into family history assessment are increasing the utility of this powerful clinical tool. Taking a traditional "targeted" family unit history may be necessary in an emergency or when time is limited, simply it should not be a substitute for maintaining a 3-generation pedigree for every patient.
Genomics Glossary
Consanguinity: A genetic relationship between persons descended from a common ancestor. Consanguinity increases the likelihood of inheriting identical versions of a given cistron.
Consultand: Person who seeks genetic counseling for knowledge about a disease or condition in the family unit.
Predictive genetic testing: Determination of genetic variation in an asymptomatic person to ascertain whether the probability for a given affliction or condition is greater than the population-based average.
Proband: The person in a family unit affected with a disease or condition that raises suspicion that other family unit members may accept an increased propensity for the same disease or status.
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REFERENCES
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3. Acheson LS, Wiesner GL. Electric current and futurity applications of genetics in primary intendance medicine. Prim Care. 2004;31:449–threescore.
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5. U.S Preventive Services Task Strength. Screening for colorectal cancer: recommendation and rationale. Ann Intern Med. 2002;137:129–31.
six. U.S Preventive Services Task Strength. Counseling in master care to promote a good for you diet: recommendations and rationale. Am J Prev Med. 2003;24:93–100.
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8. U. S. Preventive Services Task Force. Screening for abdominal aortic aneurysm: recommendation statement. Ann Intern Med. 2005;142:198–202.
ix. U. S. Preventive Services Job Force. Screening for breast cancer: recommendations and rationale. Ann Intern Med. 2002;137:344–6.
10. U. Due south Preventive Services Job Force. Screening adults for lipid disorders: recommendations and rationale. Am J Prev Med. 2001;twenty(3 suppl):77–89.
11. U.South Preventive Services Task Force. Newborn hearing screening: recommendations and rationale. Am Fam Physician. 2001;64:1995–9.
12. U.South Preventive Services Chore Force. Screening for prostate cancer: recommendation and rationale. Ann Intern Med. 2002;137:915–6.
13. U.S Preventive Services Task Force. Recommendation statement: screening for pancreatic cancer. Accessed online June 17, 2005, at:http://www.ahrq.gov/clinic/3rduspstf/pancreatic/pancrers.htm.
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xvi. Acheson LS, Wiesner GL, Zyzanski SJ, Goodwin MA, Stange KC. Family unit history-taking in community family practice: implications for genetic screening. Genet Med. 2000;2:180–5.
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twenty. Al-Hamamy H, Al-Bayati Due north, Al-Kubaisy Westward. Consanguineous matings in the Iraqi urban population and the issue on pregnancy consequence and babe mortality. Iraqi Med J. 1986;34:75–80.
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23. Offit Thou, Groeger Eastward, Turner S, Wadsworth EA, Weiser MA. The "duty to warn" a patient's family members well-nigh hereditary disease risks JAMA. 2004;292:1469–73.
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25. Baglioni S, Genuardi G. Unproblematic and complex genetics of colorectal cancer susceptibility. Am J Med Genet C Semin Med Genet. 2004;129:35–43.
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This article is ane in a series coordinated by the National Human being Genome Research Plant, National Institutes of Health, Bethesda, Md. Invitee editor of the series is Daniel J. Wattendorf, MAJ, MC, USAF.
This is one article in a series coordinated by Kenneth Lin, G.D.
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