The Spanish National Registry for Myotonic Dystrophy Type 1

Long-read genomic sequencing analyses encompassing CTG expansion characterization and whole-genome genetic and epigenetic profiling.

Biomarker evaluation

IQ, memory, attention, language

Video Hand Opening Time, clinical measure for Myotonic Dystrophy (DM1) tracking hand reopening speed

The Muscular Impairment Rating Scale is a 5-point ordinal clinical scale used to evaluate the severity of muscular impairment in patients with myotonic dystrophy.

Scores range from 1 (minimal or no impairment) to 5 (severe muscle impairment). Higher scores indicate worse functional impairment.

Hand grip strength is assessed as a measure of upper limb muscle strength using a hand-held dynamometer. Grip strength is measured separately in the dominant and non-dominant hand, and recorded in kilograms (kg).

For each hand, three consecutive attempts are performed, alternating between hands to minimize fatigue. The maximum value (best of three attempts) for each hand is recorded and used for analysis.

Higher values indicate better muscle strength and functional outcome, while lower values reflect greater muscular impairment.

Six-Minute Walk Test

10-meter Walk/Run Test

30-Second Chair Stand Test

Forced Vital Capacity (L)

The following ECG-derived parameters and abnormalities are recorded:

• PR interval duration (milliseconds)
• QRS complex duration (milliseconds)
• Presence of atrioventricular block (AV block) (yes/no), and AV block grade when present (first degree, second degree Mobitz I, second degree Mobitz II, third degree)
• Presence of supraventricular arrhythmias (yes/no)
• Presence of ventricular arrhythmias (yes/no)
• Other electrocardiographic abnormalities, recorded as free text when applicable

All measurements are extracted from the ECG tracing according to standard clinical practice.

Higher PR or QRS durations and the presence of conduction abnormalities or arrhythmias indicate greater cardiac involvement, while normal values and absence of abnormalities indicate preserved cardiac electrical function.

Body Mass Index

Collection of gynecological clinical history and relevant reproductive health events for participants who opt to provide this information.

Collection of participant-reported gastrointestinal symptoms and related clinical information.

Myotonia severity is assessed using the Myotonia Behaviour Scale (MBS), a clinician-reported ordinal scale that evaluates the functional impact of myotonia-related muscle stiffness on daily activities.

The scale ranges from 0 to 5, with higher scores indicating greater severity and functional interference due to myotonia:

0: No muscle stiffness

• Mild stiffness present but easily ignored
• Stiffness present and occasionally noticeable but does not interfere with daily activities
• Stiffness requiring increased concentration to perform certain tasks or activities
• Stiffness interfering with all tasks and daily activities
• Severe, disabling stiffness requiring constant movement to avoid complete motor blockage

Lower scores reflect minimal or absent myotonia, while higher scores reflect greater functional impairment due to myotonia.

Global disability is assessed using the Modified Rankin Scale (mRS), a widely used ordinal scale measuring the degree of disability or dependence in daily activities.

The scale ranges from 0 to 6, with higher scores indicating greater disability or death:

0: No symptoms

• No significant disability; able to carry out all usual activities despite symptoms
• Slight disability; unable to perform all previous activities but able to manage own affairs without assistance
• Moderate disability; requiring some help but able to walk without assistance
• Moderately severe disability; unable to walk without assistance and unable to attend to bodily needs without help
• Severe disability; bedridden, incontinent, and requiring constant nursing care and attention
• Death

INQoL (Individualized Neuromuscular Quality of Life Questionnaire)

FSS (Fatigue Severity Scale )

MEDAS-14 (Mediterranean Diet Adherence Screener)

DSS (Daytime Sleepiness Scale)

AES (Apathy Evaluation Scale)

IPAQ (International Physical Activity Questionnaire)

MHI-5 (Mental Health Inventory)