Makindo Medical Notes Comprehensive Medical Encyclopedia | Education for Healthcare Professionals

Taking a family history is an essential part of medical assessment, especially when evaluating patients for suspected genetic disorders. It helps identify inheritance patterns, at-risk relatives, and the need for genetic counselling or testing.

📖 Introduction

Many conditions (e.g., cystic fibrosis, Huntington’s disease, BRCA-related breast/ovarian cancer) follow recognisable inheritance patterns.
A thorough family history can guide diagnostic testing, reproductive planning, and preventive strategies.
Genetic disorders may be Mendelian (single-gene), multifactorial, or chromosomal.

📝 History Taking

Draw a family tree (pedigree) covering at least three generations.
Record: age, sex, health status, age at death, and cause of death of relatives.
Ask about: recurrent miscarriages, consanguinity, intellectual disability, congenital anomalies, early cardiovascular disease, early cancers.
Document ethnic background (some disorders are more prevalent in specific groups, e.g. sickle cell disease in Afro-Caribbean, thalassaemia in Mediterranean/South Asian).

🔬 Inheritance Patterns


Pattern	Key Features	Examples
Autosomal Dominant 👑	Vertical transmission, each child 50% risk, males & females equally affected.	Huntington’s disease, Marfan syndrome, familial hypercholesterolaemia.
Autosomal Recessive 🔄	Often siblings affected, parents usually carriers, 25% recurrence risk per pregnancy.	Cystic fibrosis, sickle cell anaemia, phenylketonuria.
X-linked Recessive ♂️	Affects mainly males, female carriers usually asymptomatic, no male-to-male transmission.	Duchenne muscular dystrophy, haemophilia A & B, G6PD deficiency.
Mitochondrial 🔋	Transmitted by affected mother to all children; affected fathers do not pass it on.	MELAS, Leber’s hereditary optic neuropathy.
Multifactorial ⚖️	Interaction of genetic susceptibility + environment; clustering in families but not Mendelian.	Type 2 diabetes, hypertension, ischaemic heart disease, asthma.

🩺 Clinical Considerations

Identify “red flag” features: early-onset cancer, multiple affected relatives, unusual phenotypes.
Assess for syndromic features (dysmorphism, organ anomalies).
Screen for associated complications (e.g. cardiomyopathy in Duchenne muscular dystrophy).

🧪 Investigations

Genetic testing: targeted mutation analysis, whole exome sequencing if appropriate.
Cytogenetic studies: karyotype, FISH, chromosomal microarray for structural changes.
Functional tests: enzyme assays, metabolic screens (urine amino/organic acids).
Imaging: cardiac echo, brain MRI if specific syndromes suspected.

⚕️ Management

📋 Genetic counselling: essential for patient and family to understand inheritance, risks, and options.
🔄 Screening of relatives: cascade testing where appropriate.
🍼 Reproductive options: prenatal diagnosis, preimplantation genetic testing, donor gametes.
💊 Treatment: some conditions amenable to targeted therapy (e.g. enzyme replacement in Gaucher disease, CFTR modulators in cystic fibrosis).
🧠 Psychological support: managing anxiety, stigma, and family planning decisions.

📚 References

NICE Clinical Knowledge Summaries – Genetics topics.
Gorlin RJ, Cohen MM. Syndromes of the Head and Neck. Oxford University Press.
Thompson & Thompson. Genetics in Medicine. 8th ed.

💡 Summary: A structured family history helps identify possible genetic disorders. Always consider inheritance patterns, red flag features, and refer to genetics services early. Genetic counselling and patient-centred communication are as vital as laboratory tests.

Family history of possible genetic disorder