My dad has dyslexia. He's the only family member that I know of that does. He's not sure if he was ever formally diagnosed but back in the day he remembers his teacher telling his parents that he was dyslexic. My father started 1st grade at 4.5. Re-read that. There was no kindergarten when he was a child so he started in 1st grade and then because he was dyslexic and having a hard time he repeated the 1st grade.
Fast forward and my youngest child is struggling in language. Oh, he's great with math and numbers. He can create mind boggling things out of stuff from my recycling bin. But learning his letters or remembering words is a struggle of epic proportions.
Not only is he speech delayed, but he can learn a letter only to "lose" it the following week when a new one is added. He also struggles to read. He's been put into the special reading lab to help youngsters catch up. And we work on these concepts daily. Daily. We also read every night and have since he was born.
But he can't see to hold those abstract concepts in his head. That's what his teachers think anyway. He's almost 6 though and they are worried that it could be something like dyslexia. For now it's too soon to give him a diagnostic. Most of the kindergarten tests are based on auditory skills. He hears just fine and like his mother, is most comfortable there. They don't start the visual testing until 1st grade.
So in the meantime, we keep plugging along and trying to make the abstract concept of 'the' as concrete for his brain as possible.
And yes, I realize the irony. My oldest child learned his letter complete with sounds when he was 3 and moved onto reading at age 4. My youngest knows a handful of letters and he's almost 6. They go at different paces and have different struggles. I should point out that my oldest has behavioral problems, which he's improved a great deal on, while my youngest received the Building Blocks Award for this month for his class. Building blocks is having good character ie behavioral traits. We just go with it.