Haplo

Haplo is a combining form and prefix used primarily in biology and medicine to denote a single set of chromosomes or a single copy of a gene. The term derives from the Greek haploos, meaning simple, single, or half, and appears in many scientific terms such as haploid, haplotype, and haplogroup.

In genetics, haploid refers to cells or organisms with one complete set of chromosomes (n). In animals and many plants, gametes (sperm and egg) are haploid, while the fusion of two gametes during fertilization forms a diploid zygote (2n). The contrast between haploid and diploid underlies patterns of inheritance and genome organization.

A haplotype is a set of genetic variants inherited together from a single parent. In population genetics, haplogroups are lineages defined by shared haplotypes, often tracing ancestry or historical migrations.

Haplodiploidy is a sex-determination system in which females are diploid and males are haploid, observed in some insects such as bees, ants, and wasps. The prefix also occurs in medical contexts, such as haploidentical transplantation, where a donor shares half of the HLA markers with the recipient, enabling certain types of stem cell or bone marrow transplants.

In pharmacogenomics and genetics, haploinsufficiency describes a situation in which a single functional copy of a gene is insufficient to maintain normal function, leading to a phenotype.

Haplo is thus a productive root in scientific terminology, often appearing as a prefix or combining form in terms describing chromosome number, lineage, or gene dosage. Related terms include haploid, haplotype, haplogroup, haplodiploidy, haploinsufficiency, and haploidentical.