Cognitive problems

I have been avoiding writing about this topic, although it is something that I think about almost every day. I avoid writing about it, because it makes me very upset and by some stupid superstitious belief, I almost feel like not writing about it is the right thing to do, but it's not really. It is a HUGE, controversial and totally under-researched topic.
Whenever you read about HCH, you will run into this extremely annoying, idiotic sentence which will go like this: about 10% of patients with hypochondroplasia seem to have learning difficulties and/or mental retardation (some will add mild/moderate, others will say moderate/severe).

There is one, really thorough, albeit very small study which had 27 people of which none had any intellectual problems...
Then there is the infamous Bellus-Francomano study, I stand open to correction, but here is what I understand happened... These 2 geneticists undertook to conduct the largest ever study on patients with hypochondroplasia,  about 300 patients were included. I think some big pharmaceutical was involved and they were going to test for HGH effectivity as well. When the HGH part fell through, the big pharma pulled the funding and the good doctors or the big pharma are now sitting on the data which has never been evaluated. My understanding is that this study wasn't an objective study as in participants didn't take IQ tests (and don't get me started about the objectivity of those...), but it was more a retrospective study where patients/parents were asked about learning difficulties, developmental delays etc. According to one source about half have claimed to have had speech/other developmental delay in both the N540K and other kind of mutation groups, which of course is significantly higher than in other populations.
The fact that the results have never been published hasn't stopped Dr. Francomano from referring to the study on the NCBI write-up about hypochondroplasia, here is what she had to say: "The authors' preliminary studies [Bellus & Francomano, unpublished results] suggest that individuals with FGFR3 N540K mutations may have an increased incidence of mild-to-moderate intellectual disability or learning disabilities."
I have written to Dr. Francomano several times and unsurprisingly never got a response, I realize she is a very busy person. I am not sure how ethical or smart it is to start referring to an unpublished study without giving any further detail and making such a vague statement. It sure is not very helpful to all parents in the zone...
I have specifically asked Dr. Pauli about what he thinks based on his 30+ years of experience and relatively large patient numbers. This is what he said:
- He does have few patients who have severe mental disability, this should be visible very early in infancy.
- He thinks that up to 50% may have some kind of an isolated learning disability, most often verbal, like speech delay or later dyslexia like - these children may need extra help to overcome this, but do well in school.
- He thinks the mental disability% is about 10%
- He also noted that most often in the literature patients with mental disability have "temporal lobe dysgenesis"
This is actually the very same phrase that is being used by most HCH patients who have seizures, you can read more about that here.
I think over the last year I have connected with at least 50 families whose children (and some parents) have hypochondroplasia. 6 have had epilepsy.
The only children I know of who have cognitive problems all have epilepsy - 3 out of the 6.
2 of them are non-verbal, 1 is attending mainstream school and is doing well with support.
Many seem to have some speech delay, which could also be attributed to the high incidence of otis media, whether that is the case or not, I guess noone knows...
When we are seeing Dr. Pauli next I will specifically ask him if in his practice there have been any children with cognitive problems and no epilepsy.
I wish we could just come up with a list of questions and ask all parents and then analyze the data, but I know that's the idealist statistical nerd in me...