Diagram the Three Described Generations of This Family in Accepted Pedigree Form
Family History: The Three-Generation Pedigree
Am Fam Physician. 2005 Aug 1;72(three):441-448.
Related Editorial
This article exemplifies the AAFP 2005 Annual Clinical Focus on the legal, social, clinical, and upstanding bug of medical genomics.
Article Sections
- Abstract
- Office Collection of Family History
- Patient Collection of Family History
- Assessment
- When Family History Suggests a Genetic Condition
- References
The drove of a family history ranges from but asking patients if family members have the aforementioned presenting disease to diagramming complex medical and psychosocial relationships as part of a family genogram. The three-generation pedigree provides a pictorial representation of diseases within a family and is the most efficient mode to assess hereditary influences on disease. Two recent events have fabricated family history cess more of import than ever: the completion of the Human Genome Project with resultant identification of the inherited causes of many diseases, and the establishment of national clinical practice guidelines based on systematic reviews of preventive interventions. The family history is useful in stratifying a patient's risk for rare single-gene disorders and more common diseases with multiple genetic and environmental contributions. Major organizations have endorsed using standardized symbols in pedigrees to identify inherited contributions to disease.
A 3-generation full-blooded has been used for diagnostic consideration or take chances assessment of rare unmarried-gene or chromosomal disorders. Still, the utility of family history in the assessment of risk for common diseases is becoming increasingly recognized.1–3 Well-nigh mutual diseases result from a combination of environmental factors and variations in multiple genes. Inherited variations within these genes confer private risks that can differ greatly from the population-based average. Assessment of family history is useful to detect increased risks for diseases that have modifiable risk 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 unit history (Table i4–xiii ). Family history assessment as well can aid identify relatively rare conditions that may not be considered in a differential diagnosis (Table 2). Alternatively, when a relatively common disease is acquired by an inherited mutation in a single cistron, family history cess may lead to early on diagnosis and more aggressive management (Table 3).
TABLE 1
USPSTF Recommendations Based on Family History
| Level | Topic | Recommendation | Clinical considerations |
|---|---|---|---|
| A | Aspirin for primary prevention of cardiovascularevents4 | Discuss aspirin chemoprevention with adults who are at increased take a chance of coronary heart disease. | Gamble cess should include questions about age, sex, diabetes, elevated total cholesterol levels, depression loftier-density lipoprotein cholesterol levels, elevated claret pressure, family history, and smoking. |
| A | Screening for colorectal cancer5 | Screen men and women l years and older for colorectal cancer. | Initiating screening at an earlier age is reasonable in persons at higher run a risk (east.k., those with a first-degree relative who receives a diagnosis earlier 60 years of age). |
| Expert guidelines be for screening very high-risk patients, including those with a history suggestive of familial polyposis or hereditary nonpolyposis colorectal cancer. | |||
| B | Behavioral counseling in primary care to promote a salubrious diet6 | Counsel adult patients with hyperlipidemia and other known risk factors for cardiovascular and diet-related chronic disease. | — |
| B | Chemoprevention of breast cancer7 | Discuss chemoprevention with women at loftier risk for chest 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 chest biopsy are the strongest risk factors for breast cancer. |
| B | Screening for abdominal aortic aneurysm8 | Perform erstwhile ultrasound screening in men 65 to 75 years of age who have ever smoked. | Major chance factors include age (65 years or older), male person sex, and a history of smoking (at least 100 cigarettes in a person's lifetime). A commencement-degree family history of intestinal aortic aneurysm that required surgical repair too increases men's risk. |
| B | Screening for breast cancer9 | Perform screening mammography, with or without clinical chest examination, every one to ii years in women 40 years of age and older. | Women at increased take a chance for breast cancer (due east.g., those with a family history of breast cancer in a mother or sister, a previous breast biopsy revealing atypical hyperplasia, kickoff childbirth after age 30) are more likely to benefit from regular mammography than women at lower take chances. |
| B | Screening for lipid disorders in adults10 | Screen men 20 to 35 years of age and women xx to 45 years of age with diabetes, a family unit history of cardiovascular disease before age fifty in male person relatives or age sixty in female relatives, or a family unit history suggestive of familial hyperlipidemia. | — |
| D | Screening for pancreatic cancer11 | Do not screen routinely for pancreatic cancer in asymptomatic adults using abdominal palpation, ultrasonography, or serologic markers. | Persons with hereditary pancreatitis may have a higher lifetime take chances for developing pancreatic cancer. |
| I | Screening for prostate cancer12 | Evidence is insufficient to recommend for or confronting routine screening for prostate cancer using prostate-specific antigen testing or digital rectal examination. | Men older than 45 years of age who are at increased risk (e.one thousand., black men, men with a family history of prostate cancer in a offset caste relative) are virtually likely to benefitfrom screening. |
| I | Newborn hearing screening13 | Evidence is insufficient to recommend for or confronting routine screening of newborns for hearing loss during postpartum hospitalization. | The screening yield and proportion of truthful-positive results will be substantially higher when screening is targeted at high-risk infants (e.1000., 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 childhood sensorineural hearing loss, congenital infections, and craniofacial abnormalities). |
TABLE ii
Symptoms and Family History Suggestive of Single-Cistron Disease
| Primary symptom | Family history | Illness | 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, cognitive aneurysm, or renal failure | Autosomal-dominant PKD | ADPKD1, ADPKD2 |
| Shortness of breath | 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 |
Tabular array iii
Common Diagnoses Suggestive of Single-Gene Disease
| Diagnosis | Family history | Disease etiology | Factor |
|---|---|---|---|
| DVT | DVT, pulmonary embolism | Hereditary thrombophilia | Multiple; F5 |
| Nigh common: activated protein resistance-factor V Leiden | |||
| Emphysema | Emphysema | α-1 antitrypsin deficiency | SERPINA |
| Glaucoma (main open-angle) | Glaucoma | Hereditary glaucoma | MYOC |
| Pancreatitis | Pancreatitis | Hereditary pancreatitis | PRSS1 |
Prevention efforts are enhanced by family unit discussions that shed calorie-free on lifestyles or family behaviors that have agin health consequences. Prevention also is accomplished by identifying patients with a higher chance than the population average because of shared inherited factors associated with affliction. In some cases, standard screening may be supplanted by targeted genetic testing and a change in clinical intervention for persons at high risk for affliction, such as those with a stiff family history of cancer.
Part Collection of Family History
- Abstract
- Office Collection of Family History
- Patient Collection of Family History
- Assessment
- When Family unit History Suggests a Genetic Condition
- References
Physicians can use several approaches to collect family unit information and construct a full-blooded. The most traditional approach is physician-directed questioning of the patient or family informant. Nurses, physician assistants, and other trained clinical staff also may complete this process. This approach typically takes 15 to thirty minutes. Alternatively, patients can be provided with questionnaires about their family history information before an office visit. This method still requires a health professional to review the information and create a pedigree.
Unfortunately, a health maintenance visit does not permit for this amount of time to devote to family history collection.14 In reality, the average office visit lasts 16 minutes, and family history give-and-take has been observed to last less than iii minutes.15,16 Many physicians compensate for this time limitation past collecting family history information piecemeal over several visits. Checklists may exist used in an attempt to speed data collection, simply the usefulness of this approach may be limited past patient recollect. Checklists likewise may non distinguish which relatives are affected or their degree of relatedness to the patient. Additionally, unknown family medical information, a patient's focus on an acute problem, and fear of bigotry may impede collection of a consummate and accurate family history.
Patient Collection of Family unit History
- Abstract
- Role 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 developed a pocket guide that provides instructions and examples for patients on how to generate a pedigree. Information technology is bachelor online athttp://www.ama-assn.org/ama/pub/category/2380.html.
A print and Spider web-based tool developed equally part of the U.South. Surgeon General's Family History Initiative17 is available online athttp://www.hhs.gov/familyhistory. This tool, which is bachelor in English and Spanish, guides the collection of family history, which is then transferred to a printable, standardized, three-generation pedigree. Specific questions target six developed diseases: middle disease; diabetes; stroke; and breast, ovarian, and colon cancers. These diseases are highlighted because they are mutual and require a change in clinical evaluation or intervention based on family history. Families are encouraged to seek specific information directly from family members, their physician, and medical records.
Assessment
- Abstract
- Office Collection of Family History
- Patient Collection of Family History
- Assessment
- When Family History Suggests a Genetic Condition
- References
Regardless of whether family unit history was collected in the md's function or the patient'south home, assessment should occur at the initial patient evaluation and exist updated periodically to identify newly diagnosed medical or developmental weather within the family. Physicians should begin with recording the current age and historic period at onset of symptoms or diagnosis of the patient and first-, second-, and 3rd-degree relatives on each side of the family. The age and cause of death for deceased family members too should be recorded. The accuracy of information by and large decreases as the degree of relatedness decreases. Therefore, physicians should notation when data is from a medical source instead of a family report.
The most useful family history includes medical, developmental, and pregnancy outcome information on showtime-, second-, and third-degree relatives.18 The degree of relatedness indicates the pct of shared genes (Table four). For example, the half-sibling and the uncle of a patient inherit the aforementioned proportion of genes (25 percent) identical to the patient'due south. Standard symbols and diagrams allow rapid attribution of diseases to particular branches of the family ( Effigy 1 nineteen). Having 2 relatives from the same 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 class of colon cancer) more than than if one relative was from the paternal side of the family and the other from the maternal side.
Table 4
Shared Genes in Blood Relatives
| First-degree relative (fifty% shared genes) | Second-degree relative (25% shared genes) | Third-degree relative (12.five% shared genes) |
|---|---|---|
| Children | Aunts and uncles | Cousins |
| Parents | Grandparents | Nifty-grandparents |
| Siblings | Half siblings | |
| Nieces and nephews |
Pedigree Symbols
Figure 1.
Standard pedigree symbols used in the collection of a family history.
Medical information oftentimes is not known because of generational, cultural, or wellness literacy issues. For instance, older relatives mistakenly may believe that give-and-take of a cancer diagnosis is futile, because in the past there was not effective treatment. A couple planning to have children may non know the relevance of inquiring virtually previous miscarriages in the family, and family unit members may not volunteer this emotionally sensitive information. Conditions that are idea to occur sporadically actually could be inherited. For example, a family history of multiple relatives with Downward syndrome suggests an inherited translocation, non desultory non-disjunction. A woman may not realize that her paternal grandmother's and aunt'southward breast cancer diagnoses confer the same risk to her equally if they were maternal relatives. Therefore, encouraging ascertainment of health information for iii generations of relatives is warranted.
Consanguinity, the shared relationship of a mutual 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 mutual share a greater proportion of genes. In Republic of iraq, for example, 29.ii percent of marriages are between first cousins, and 57 percent of marriages demonstrate some amount of consanguinity.20 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 same mutation in a cistron.21 Recurrence of common circuitous diseases also may be 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 unmarried factor may have genetic variations whose frequencies differ depending on ancestral 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. Only if the patient or partner has an ancestor from southeast Asia, in that location is an increased take a chance of thalassemia H or fifty-fifty 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 carrying 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 effective treatment possible.
The recall of spontaneous abortions, stillbirths, illnesses, and deaths of family members may evoke stiff emotional responses in patients. Feelings of guilt and arraign are not unusual in families in which several relatives are affected by the same condition. 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 advisor may be helpful, although genetics professionals are not widely available. Actress clinic fourth dimension and the assistance of mental wellness professionals may be required.
Relatives sometimes may exist identified who accept significant gamble for a disease and in whom early on intervention may better outcomes. The patient should be encouraged to notify these family members of their risk and refer them to a doc. In these cases, the physician'southward obligation to warn other family members directly is not clear.23 There accept been successful claims of negligence confronting physicians for failure to warn patients that their family unit members were at increased adventure for colon and breast cancers.24
The verbal duty of the physician in these instances often is untested, particularly given the restrictions of the Health Insurance Portability and Accountability Deed, and is subject field to individual state court interpretation. Therefore, disclosure to other family members must exist considered advisedly with respect to privacy and weighed against a duty to warn.
When Family History Suggests a Genetic Status
- Abstract
- Office Collection of Family History
- Patient Collection of Family History
- Assessment
- When Family History Suggests a Genetic Status
- References
In some patients, the family history may be pregnant plenty (due east.g., multiple affected relatives with early onset of a disease) to consider genetic testing for an identified or suspected mutation in a unmarried cistron. If the tested cistron is a component of a complex affliction, a establish mutation offers susceptibility or predictive, but not confirmatory, data. The degree of gamble attributable to variations or mutations in a single factor can range from a modest contribution in circuitous affliction to near 100 percent certainty. For example, a variation in the APC factor establish in the Ashkenazi Jewish population confers a modest risk of colorectal cancer.25 Other mutations in the same gene cause familial adenomatous polyposis with a nearly 100 percent lifetime risk of colorectal cancer.
Susceptibility or predictive testing for familial cancers may significantly subtract morbidity or mortality past changing the management of the disease. Alternative screening with lower specificity only higher sensitivity may be sought (e.k., magnetic resonance imaging for early breast cancer detection), and chemoprophylaxis may be offered (eastward.1000., tamoxifen [Nolvadex] for chest cancer prevention). Aggressive screening and surgical prophylaxis may be initiated (e.m., colonoscopy for detection and removal of precancerous lesions in patients with hereditary nonpolyposis colon cancer). Early on surgical intervention may exist recommended every bit preventive measures (east.g., in family members of a patient with a mutation of the MEN2A cistron who inherit a mutation in the RET cistron and are nigh certain to develop medullary thyroid carcinoma) or offered (e.thousand., mastectomy or oophorectomy may exist called by patients with an unidentified BRCA1/2 mutation). Predictive testing for noncancerous conditions also may exist initiated. In an adult who has asthma that cannot exist improved with bronchodilators, the riskof α-1 antitrypsin deficiency increases if at that place is a family history of emphysema or bronchiectasis. If airf low obstruction is found to exist incompletely reversible on pulmonary function testing, the patient is a candidate for genetic testing.26
Family history also may guide diagnosis fifty-fifty when DNA-based genetic testing is not available for an inherited condition. In a child presenting with a syncopal episode, a family unit history of syncope prompts consideration of long QT syndrome.27 In an adult presenting with fatigue or arthralgias, a family history of diabetes and cirrhosis should betoken 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 history may be necessary in an emergency or when fourth dimension is limited, but it should not be a substitute for maintaining a three-generation pedigree for every patient.
Genomics Glossary
Consanguinity: A genetic relationship betwixt 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 cognition about a disease or condition in the family.
Predictive genetic testing: Decision of genetic variation in an asymptomatic person to ascertain whether the probability for a given disease or status is greater than the population-based boilerplate.
Proband: The person in a family affected with a disease or condition that raises suspicion that other family members may have an increased propensity for the same disease or status.
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This article is one in a series coordinated by the National Man Genome Research Institute, National Institutes of Health, Bethesda, Medico. Guest editor of the serial is Daniel J. Wattendorf, MAJ, MC, USAF.
This is one article in a series coordinated by Kenneth Lin, M.D.
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