Topic Specific Rules

Assays or Procedures

Why does the HPO include the assay name in some terms but not in others?

There are some medical assays or procedures such as the electrocardiogram (EKG or ECG) and the electroencephalogram (EEG) that make measurements in ways that cannot be duplicated by other technologies. In these cases, it often seems clearer to include the name of the assay or procedure in the primary term label because it will be more easily recognizable to clinicians. In other cases, an underlying abnormality can be diagnosed by two or more technologies. In this case, the HPO does not include a separate term for each technology. For instance, certain neuroanatomic anomalies such as Aplasia of the corpus callosum can be imaged with either computed tomography (CT) or magnetic resonance imaging (MRI). In this case, the HPO does not have two separate terms such as Aplasia of the corpus callosum by CT and Aplasia of the corpus callosum by MRI, but instead just has a single term. The comment of the term can be used to state that the anomaly can be ascertained by CT or by MRI if desired.

Ophthalmology abnormalities

Electroretinogram (ERG)

Definitions are derived from McCulloch DL et al. 2015 (PMID:25502644).

Skeletal abnormalities

Delayed vs. Poor ossification

Ossification of the spine starts in the thoracic region and spreads both caudally and rostrally. So a fetus with poorly ossified cervical and sacral vertebrae (at an age when these should be ossified) could be described as having delayed ossification. In contrast, vertebral bodies in hypophosphatasia, for example, are poorly ossified in general. So a distinction makes sense. It is possible also that the mechanisms for delayed ossification could be quite different from those of poor ossification, so another reason to keep them separate.

The HPO will make ‘delayed ossification’ a child of ‘poor ossification’ as its a more specific pattern of poor ossification. This way people can use the correct term if they want to be precise, but those who call everything ‘poor ossification’ will not be far off in the tree. (comments adapted from Prof. A. Zankl)

Delayed ossification of X
A decrease in the amount of mineralized bone in X compared with that expected for a given developmental age.

Nephrology

The following descriptors are recommended for renal terms.

Specifiers for glomerular phenotypes

• Focal: Involving some but not all glomeruli
• Segmental: Involving some of but not all of each glomerulus
• Diffuse: Involving all glomeruli
• Global: Involving all of each affected glomerulus

Focal segmental glomerulosclerosis
Focal global glomeruloslcerosis
Diffuse segmental proliferative GN 

Synonymous terms

• Mesangiocapillary GN is completely synonymous with Membranoproliferative GN. Mesangial proliferative means increased mesangial cells.

• "Proliferation" is now being replaced with "hypercellularity."

• "Capillary wall" and "membrane" are used almost interchangeably in light microscopy reports. Location of electron dense deposits is determined by Electron Microscopy: Mesangial, subepithelial, intramembranous, subepithelial.

• Subepithelial deposits can be large and are termed "humps."

• Fibrin deposition on EM often is described as "lucent" or "flocculent" material.

• Amyloid deposition is defined by positivity for Congo Red staining. On EM amyloid is disorganized fibrils. Organized fibrils are immunotactoid.

• Tubular atrophy, tubulointerstitial fibrosis, interstitial fibrosis tubular atrophy=IFTA, interstitial scarring are all essentially synonymous.