Learning disabilities are disorders that affect brain functioning of understanding, reading, writing, spelling, reasoning or recalling ability. Learning disabilities can also cause problems in learning skills, language skills, mathematical operations, and coordinating movements. Learning disabilities are continual and can cause continual life-long challenges. Children with learning abilities often have average or above-average intelligence. Learning Disabilities are not contagious. Learning Disabilities are due to genetic or neurobiological factors which affect cognitive processes related to learning. Learning Disabilities can run in those whose paternal relatives have such problems (genetic), but environmental factors can also play an important role

Difficulty in recalling sequence of letters in words and frequent loss of visual memory is associated with, language-based disability, "Dyslexia". Dyslexia is the most common learning disability.  Dyslexia is a language-based disability in which a person faces problems in understanding written words. It is also referred to as a reading disorder.  

A child suffering from Dyslexia may find it difficult to distinguish between words, 'nest' and 'best' , 'glow' and 'slow'.

Common Learning Disabilities:

• Dysgraphia: Dysgraphia is a writing disability in which a person finds it hard to form letters or write within a defined space. It affects a person's handwriting ability. A person with Dysgraphia may exhibit difficulty with letter spacing, trouble thinking, and writing simultaneously.
• Dyscalculia:  Dyscalculia is a mathematical disability in which a person's ability to understand numbers and grasping math concepts is affected.
• Dyspraxia:  Dyspraxia is a neurological disorder that impacts an individual ability to plan process motor tasks.
• Nonverbal Learning Disabilities: It actually refers to difficulties in decoding nonverbal behaviors or social clues. NVLD suffers struggle with understanding body language, facial expressions, tone of voice, or nonverbal aspects of communication.

Hence, Difficulty in recalling the sequence of letters in words and frequent loss of visual memory is associated with, language-based disability, "Dyslexia".