What genetic traits can be inherited from one's mother?

Genetic Traits Inherited from Mother

All mitochondrial DNA (mtDNA) is exclusively inherited from the mother through the egg cell cytoplasm, while nuclear DNA traits can be inherited from either parent depending on the inheritance pattern. 1

Maternal-Only Inheritance: Mitochondrial DNA

• Mitochondrial DNA is transmitted exclusively through the maternal line to all children, regardless of their sex. 1, 2
• The mitochondrial genome contains 37 genes encoded by approximately 16,569 base pairs that are essential for cellular energy production through oxidative phosphorylation. 3, 4
• Males with mtDNA mutations have zero risk (0%) of transmitting these mutations to their offspring because sperm contribute only nuclear DNA to the fertilized egg. 1, 5
• Each cell contains thousands of copies of mtDNA, and mutations can affect all copies (homoplasmy) or only a portion (heteroplasmy), which influences disease severity. 5, 6

Mitochondrial Diseases from Mother

• Mitochondrial disorders are maternally inherited and can cause diverse clinical presentations including myoclonic epilepsy (MERRF syndrome), progressive vision and hearing loss, muscle weakness, and cardiomyopathy. 1, 5
• Organs with high energy requirements—brain, muscle, heart, liver, and kidney—are particularly vulnerable to mitochondrial dysfunction. 5, 4
• The phenotypic severity depends on the percentage of mutant mtDNA load (heteroplasmy level), the specific mutation, and tissue susceptibility. 5, 6
• Mitochondrial DNA mutations accumulate during life and are associated with age-related diseases including neurodegenerative disorders, diabetes, and cancer. 2, 3

Nuclear DNA Inheritance from Mother

Nuclear DNA traits follow standard Mendelian inheritance patterns, meaning traits can be inherited from the mother through autosomal dominant, autosomal recessive, or X-linked mechanisms. 5

Autosomal Dominant Inheritance

• Hereditary cancer syndromes like BRCA1/BRCA2 mutations show vertical transmission through either mother or father with a 50% risk to each offspring. 5
• These mutations are associated with high-penetrance genotypes, early age of onset, and association with multiple tumor types (breast, ovarian cancer). 5
• Maternal family history of breast cancer diagnosed before age 50, bilateral breast cancer, or ovarian cancer significantly increases risk. 7, 5

Autosomal Recessive Inheritance

• Metabolic disorders like Anderson-Fabry disease and other lysosomal storage diseases require inheriting one mutated copy from each parent. 5
• The child must receive the recessive allele from both mother and father to manifest disease. 5

X-Linked Inheritance

• Mothers can be carriers of X-linked conditions and pass them to sons (who will be affected) or daughters (who will be carriers). 5
• Examples include some forms of muscular dystrophy and certain metabolic disorders affecting mitochondrial function. 5

Clinical Assessment Considerations

Family History Evaluation

• Both maternal AND paternal family histories must be evaluated independently—a common pitfall is focusing only on the maternal side. 5, 7
• Document ages, diseases, and causes of death for all relatives out to third-degree relatives (cousins), with verification of cancer diagnoses from medical records. 5, 7
• Limited family structure (small families, few female relatives) can lead to underestimation of genetic risk. 7

High-Risk Maternal Features

• Multiple first-degree maternal relatives with breast or ovarian cancer, especially diagnosed before age 50. 7, 5
• Maternal relatives with bilateral breast cancer or multiple primary cancers. 7
• Ashkenazi Jewish maternal heritage significantly increases BRCA1/2 mutation risk. 5, 7
• Male breast cancer in maternal lineage strongly suggests BRCA2 mutations. 7, 5

Genetic Counseling Priorities

• For mitochondrial disorders, emphasize zero transmission risk from affected fathers and 100% transmission risk from affected mothers to all children. 1
• For nuclear DNA mutations, explain the 50% risk per pregnancy for autosomal dominant conditions inherited from either parent. 1, 5
• Genetic testing should confirm whether the condition is due to mtDNA versus nuclear DNA mutations, as this fundamentally changes inheritance counseling. 1, 5