Left ventricular noncompaction (LVNC) is a condition of the heart where the walls of the left ventricle, the bottom left chamber of the heart, retain an unusually loose or spongy texture (non-compacted). This leads to the formation of trabeculations, or channels, in the heart muscle, giving the left ventricle a spongey, honeycomb-like appearance.

While it predominantly affects the left ventricle, it can also involve the right ventricle. LVNC can impact the heart's ability to pump blood effectively and may lead to arrhythmias. It is sometimes associated with other forms of cardiomyopathy, such as dilated or hypertrophic cardiomyopathy.

The following diagram, courtesy of CardiomyopathyUK

LVNC can be caused by changes in genes that encode for proteins that are involved in the development and function of the heart muscle. LVNC can be inherited in an autosomal dominant or autosomal recessive manner, depending on the specific gene involved. In some cases, LVNC can also be caused by new (de novo) gene changes which occur spontaneously and are not inherited from either parent.

LVNC can be caused by mutations in genes that encode for proteins that are involved in the development and function of the heart muscle. These proteins include sarcomeric proteins, cytoskeletal proteins, and transcription factors.

LVNC can be inherited in an autosomal dominant or autosomal recessive manner, depending on the specific gene involved. 

Mutations in the MYH7 gene are the most common cause of familial LVNC. MYH7 encodes for beta-myosin heavy chain, which is involved in the contraction of heart muscle cells. Other genes that have been linked to LVNC include MYBPC3, TTN, and ACTC1.

Genetic testing is not always necessary for diagnosing LVNC. The condition can also be diagnosed based on clinical symptoms, such as an enlarged heart or reduced heart function.

While LVNC is a genetic disorder, it is important to note that not all cases of LVNC are caused by genetic variants. Some cases may be due to other factors, such as viral infections or inflammation.