Generally aneuploidy (wrong number of chromosomes) in any of the larger chromosomes is embryonic lethal - that is embryos with lacking a copy or with an extra copy of one of the chromosomes are generally aborted spontaneously, resulting in a miscarriage. Aneuploidy will generally only result in a viable fetus if it is in one of the smaller chromosomes (e.g. trisomy 21 - Down Syndrome). Viable monosomies are even more rare, although some exist (e.g. XO - Turner's syndrome). To the best of my knowledge, monosomy 5 would be embryonic lethal. However, there is a condition called cri du chat syndrome in which the affected individual is lacking a portion of one of his/her copies of chromosome 5.