Db	Link	Name	Definition	Comment	Is a
HPO	HP:0000252	Microcephaly	"Head circumference below 2 standard deviations below the mean for age and gender." [PMID:15806441, PMID:19125436, PMID:25465325, PMID:9683597]	Head circumference is measured from just above the glabella (the most prominent point on the frontal bone above the root of the nose) to the most posterior prominent point of the occipital bone using a tape measure. Some standard charts are organized by centiles, others by standard deviations. It is important to add an indication of how far below the normal standard the head circumference is if an accurate assessment of this can be made. Microcephaly is an absolute term. The term relative microcephaly can be used when the head size centile is less than the centile for height, for example, head size at the 3rd centile with height at the 75% for age and sex. On prenatal ultrasound, microcephaly is diagnosed if the head circumference or the biparietal diameter is more than three standard deviations below the mean. Microcephaly is divided into primary microcephaly, which is present at birth, and secondary microcephaly, which develops postnatally. The crucial difference between these groupings is that primary microcephaly is usually a static developmental anomaly, whereas secondary microcephaly indicates a progressive neurodegenerative condition	HP:0007364, HP:0040195
HPO	HP:0000490	Deeply set eye	"An eye that is more deeply recessed into the plane of the face than is typical." [PMID:19125427]	This finding should be distinguished from a prominent supraorbital ridge or inferior orbital margin. In Deeply set eyes, the globe is recessed in comparison to the overall prominence of the face. There is no known objective measurement, and diagnosing this feature depends heavily on the experience of the observer.	HP:0100886
HPO	HP:0000089	Renal hypoplasia	"Hypoplasia of the kidney." [HPO:probinson]	Oligomeganephronic renal hypoplasia differs from simple hypoplasia, in which the renal mass is reduced but the number of nephrons is normal.	HP:0008678
HPO	HP:0000319	Smooth philtrum	"Flat skin surface, with no ridge formation in the central region of the upper lip between the nasal base and upper vermilion border." [PMID:19152422]	There is a spectrum of this finding from total absence of the philtral ridges to a some prominence of the ridges. The central groove varies from absent to shallow. Normal values for the frequency of smooth philtrum are available. Grading of the smoothness of the philtrum, used in the assessment of Fetal Alcohol Syndrome, has been developed. This finding is greatly influenced by the facial expression, and care should be taken to evaluate the philtrum when the face is in a neutral position. A smooth philtrum can be associated with a Long philtrum. However, the two findings should be coded separately.	HP:0000288
HPO	HP:0001974	Leukocytosis	"An abnormal increase in the number of leukocytes in the blood." [HPO:probinson]	—	HP:0011893
HPO	HP:0430009	Hypoplasia of eyelid	"Developmental hypoplasia of the eyelid." [GOC:MG]	—	HP:0011226
HPO	HP:0000609	Optic nerve hypoplasia	"Underdevelopment of the optic nerve." [HPO:probinson]	—	HP:0002977, HP:0008058
HPO	HP:0008734	Decreased testicular size	"Reduced volume of the testicle (the male gonad)." [HPO:probinson]	—	HP:0000050, HP:0010468