Laminopathy

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Laminopathy
Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Muscle weakness, cardiomyopathy, lipodystrophy, premature aging
Complications	Heart failure, arrhythmias, diabetes mellitus
Onset	Varies by specific condition
Duration	Chronic
Types	Emery-Dreifuss muscular dystrophy, Dilated cardiomyopathy, Hutchinson-Gilford progeria syndrome, Familial partial lipodystrophy
Causes	Mutations in LMNA gene
Risks	Genetic inheritance
Diagnosis	Genetic testing, muscle biopsy, echocardiogram
Differential diagnosis	Muscular dystrophy, progeroid syndromes, lipodystrophy syndromes
Prevention	Genetic counseling
Treatment	Symptomatic management, cardiac monitoring, physical therapy
Medication	ACE inhibitors, beta blockers, insulin
Prognosis	Varies by specific condition
Frequency	Rare
Deaths	N/A

Normal nuclear lamina (a and b) and mutant nuclear lamina (c and d) from a patient with HGPS

Laminopathies are a subset of genetic disorders that arise from mutations in genes responsible for encoding proteins of the nuclear lamina. Part of a broader category termed nuclear envelopathies, these diseases relate to defects in the nuclear envelope. Ever since the identification of laminopathies in the late 1990s, extensive research has begun to shed light on the critical role nuclear envelope proteins play in maintaining cellular and tissue integrity in animals.

Symptoms

Laminopathies, together with other nuclear envelopathies, manifest in a wide range of clinical symptoms. Notable among these are:

• Skeletal and cardiac muscular dystrophies
• Lipodystrophy and diabetes
• Dermal and neuropathic conditions
• Dysplasia
• Leukodystrophy
• Progeria (premature aging)

While most symptoms tend to emerge postnatally, specifically during childhood or adolescence, certain laminopathies might result in premature mortality. For instance, mutations within the lamin B (LMNB1 gene) can prove lethal either at or before birth.

Genetics

Fundamentally, individuals diagnosed with a classic laminopathy exhibit mutations in the LMNA gene, which encodes for lamin A/C. Later discoveries have linked mutations in the lamin B (LMNB2 gene) and genetic defects that alter lamin B abundance to laminopathies. Other implicated genes in nuclear envelopathies encode for lamin-binding proteins such as:

• Lamin B receptor (LBR gene)
• Emerin (EMD gene)
• LEM domain-containing protein 3 (LEMD3 gene)
• Prelamin-processing enzymes like the zinc metalloproteinase STE24 (ZMPSTE24 gene)

Laminopathies can stem from both recessive and dominant alleles, with rare instances of de novo mutations generating dominant alleles that may prevent carriers from reproducing before they perish. The most prevalent nuclear envelopathy in humans is the Emery-Dreifuss muscular dystrophy, which is traced back to an X-linked mutation in the EMD gene encoding for emerin. This condition affects approximately 1 in 100,000 individuals.

External links

• GeneReview/NIH/UW entry on LMNA-Related Dilated Cardiomyopathy

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