Categories: Mortality / aging (incl. embryonic lethal)

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal recessive

Disease-related: yes

Key variant known: no

Species-specific symbol: NH2

Mapping: By analysing Illumina Bovine 50k Beadchip genotype data from 47,878 Holstein, 16,833 Montbéliarde and 11,466 Normande cattle in the French genomic selection database, Fritz et al. (2013) identified 34 common (>1%) haplotypes that have a significant deficit (P<10^-4) of homozygotes in live animals, and which are, therefore, each likely to harbour a deleterious mutation. Three of these haplotypes, namely BY (Brachyspina; OMIA 000151-9913), HH1 (OMIA 000001-9913) and HH3 (OMIA 001824-9913), had been reported by VanRaden et al. (2011; J Dairy Sci 94:6153-61). Following the convention of naming such haplotypes with a first letter indicating breed, a second letter H for haplotype, followed by a sequential number, Fritz et al. (2013) named their 14 new Holstein haplotypes as HH4 to HH17, their 11 Montbéliarde haplotypes as MH1 to MH11, and their six Normande haplotypes as NH1 to NH6. Analyses of reproductive data indicated that nine of the 34 haplotypes have a significant effect on fertility, including six of the newly identified haplotypes, namely HH4, HH5, HH6, MH1, MH2 and NH5. This present OMIA entry is for NH2, which is located in chromosome BTA1, at 145.7–146.8Mb (UMD 3.1 genome assembly) (Fritz et al., 2013). Mesbah-Uddin et al. (2019) "assume that NH2 was a false positive because of the lower power of detection in the analysis of Fritz et al. (2013) compared with that of the current study. Indeed, the present data set is 7-fold larger than the previous one, and the frequency of NH2 more than doubled in the population, which increased the probability of observing homozygotes."

Prevalence: The NH2 haplotype occurs with a frequency of 3.8% in the 11,466 Normande adult cattle adult sampled by Fritz et al. (2013), but with only 29% of the expected frequency of homozygotes.

Breed: Normande (Cattle) (VBO_0000322).
Breeds in which the phene has been documented. (If a likely causal variant has been documented for the phene, see the variant table breeds in which the variant has been reported).