Through the use of pooled-template massively parallel sequencing, we identified 130 novel FMR1 sequence variants in a population of 963 developmentally delayed males without CGG-repeat expansion mutations.
Moreover, Eftud2 heterozygous embryos were born at the expected Mendelian frequency, and were viable and fertile despite being developmentally delayed.
In addition, tracheal-rescued ADCK1 mutant adults have reduced lifespan, are developmentally delayed, have reduced body size, and normal levels of basic metabolites.
The developmental data revealed that TCF4 (+/+) individuals were only moderately developmentally delayed while TCF4 (+/-) individuals failed to reach developmental milestones beyond those typically acquired by 12 months of age.
In light of the data presented we discuss the possible phenotypic modulatory effects of the supernumerary wild type X allele and pattern of X chromosome inactivation and stress the importance of considering the causal involvement of CDKL5 in developmentally delayed males with early-onset seizures.