Signs and Symptoms of Heart-Hand Syndrome

Heart-Hand Syndrome, Slovenian type is characterized by a “mix-and-match” set of signs that affect the hands and the heart. Because of the way the LMNA gene variant works, the condition is highly heterogeneous (variable), meaning it can look very different from one person to the next, even among close family members ^[1].

While the condition is rare, researchers have identified patterns based on the original family identified with this variant, focusing on the shape of the fingers and the electrical health of the heart’s upper chambers.

Hand and Limb Features: Brachydactyly

The most visible sign of this condition is brachydactyly, which simply means “short digits” (fingers or toes) ^[1].

• Physical Appearance: The fingers may appear shorter than average. This shortening occurs because the bones within the hand (metacarpals) or the fingers (phalanges) did not grow to their full length ^[1].
• Variable Patterns: Not everyone with the genetic variant will have short fingers. In the original family studied, about 60% of those carrying the variant had noticeable brachydactyly (a specific family finding, not a population rule), while the others had typical hand appearances ^[1].
• Symmetry: The shortening often affects both hands, though the degree of shortening can vary between individual fingers.

Unlike some other heart-hand syndromes, the Slovenian type typically does not involve major bone issues in the forearms or the “radial ray” (the thumb side of the arm) ^[1].

Cardiac Features: Electrical and Structural Changes

The heart involvement in the Slovenian type has been described in the original family as having an “atrial-predominant phenotype”—meaning signs were largely concentrated in the atria (the two upper chambers of the heart that receive blood) ^[1]. However, as with other LMNA conditions, issues in the lower chambers (ventricles) or conduction blocks can also occur.

Electrical Changes (The ECG)

One of the earliest ways doctors monitor the condition is through an Electrocardiogram (ECG), which measures the heart’s electrical activity. Specialized findings reported in this syndrome include:

• Prolonged P-wave: The P-wave is the part of the ECG strip that represents the electrical signal traveling through the atria. In some patients, that signal takes longer than normal, leading to a wider P-wave on the test ^[1].
• Atrial Arrhythmias: Electrical instability in the atria can lead to irregular heart rhythms (arrhythmias), such as atrial fibrillation (a chaotic, rapid rhythm) or atrial flutter ^[1][2].
• Conduction Blocks: The electrical signal traveling from the top to the bottom of the heart can slow down or get blocked, which can cause the heart rate to drop too low ^[3].

Muscle and Contraction Changes

Beyond electrical signals, the actual muscle of the heart may be affected.

• Reduced Atrial Contraction: Echocardiograms (heart ultrasounds) in some reported individuals showed a “reduced peak A-wave velocity,” a technical measurement suggesting the atrial squeeze may be weaker than normal ^[1]. Note that A-wave velocity can be influenced by many other general cardiac factors.
• Microscopic Findings: Experimental models and pathology studies have described “atrial lesions” or structural abnormalities in the cells ^[1]. This is a research finding to explain the biology, not a routine clinical diagnosis your doctor will look for on a standard scan.
• Cardiomyopathy: The lower chambers can also weaken over time (dilated cardiomyopathy), making it harder for the heart to pump blood effectively ^[3].

Variable Expression and Age-Dependence

It is important to understand that having the genetic variant (LMNA p.Arg335Trp) does not mean you will have every symptom.

• Incomplete Penetrance: Some people carry the gene variant but show no signs of hand or heart issues at the time they are tested ^[1].
• Independent Symptoms: In the known pedigree, some individuals had only hand features, some had only heart features, and some had both ^[1].
• Age-Dependent Nature: While we do not have a “countdown” for how quickly the condition moves, LMNA-related heart disease may be age-dependent. This means a person who has a normal heart rhythm today may develop atrial issues, conduction blocks, or heart muscle weakness later in life ^[4][5].

Because the heart disease can be “silent” before it causes symptoms like fainting or breathlessness, regular cardiac check-ups are essential to monitor for changes ^[1][2].