U.S. flag

An official website of the United States government

Format

Send to:

Choose Destination

Foveal hypoplasia - optic nerve decussation defect - anterior segment dysgenesis syndrome(FHONDA; FVH2)

MedGen UID:
814203
Concept ID:
C3807873
Disease or Syndrome
Synonyms: Foveal hypoplasia 2; FOVEAL HYPOPLASIA 2 WITH OPTIC NERVE DECUSSATION DEFECTS AND ANTERIOR SEGMENT DYSGENESIS WITHOUT ALBINISM; FOVEAL HYPOPLASIA 2 WITH OR WITHOUT MICROPHTHALMIA OR COLOBOMA; FOVEAL HYPOPLASIA 2 WITH OR WITHOUT OPTIC NERVE MISROUTING AND/OR ANTERIOR SEGMENT DYSGENESIS
Modes of inheritance:
Autosomal recessive inheritance
MedGen UID:
141025
Concept ID:
C0441748
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele).
 
Gene (location): SLC38A8 (16q23.3)
 
Monarch Initiative: MONDO:0012216
OMIM®: 609218
Orphanet: ORPHA397618

Definition

Foveal hypoplasia is defined as the lack of foveal depression with continuity of all neurosensory retinal layers in the presumed foveal area. Foveal hypoplasia as an isolated entity is a rare phenomenon; it is usually described in association with other ocular disorders, such as aniridia (106210), microphthalmia (see 251600), albinism (see 203100), or achromatopsia (see 216900). All reported cases of foveal hypoplasia have been accompanied by decreased visual acuity and nystagmus (summary by Perez et al., 2014). For a discussion of genetic heterogeneity of foveal hypoplasia, see FVH1 (136520). [from OMIM]

Clinical features

From HPO
Astigmatism
MedGen UID:
2473
Concept ID:
C0004106
Disease or Syndrome
Astigmatism (from the Greek 'a' meaning absence and 'stigma' meaning point) is a condition in which the parallel rays of light entering the eye through the refractive media are not focused on a single point. Both corneal and noncorneal factors contribute to refractive astigmatism. Corneal astigmatism is mainly the result of an aspheric anterior surface of the cornea, which can be measured readily by means of a keratometer; in a small fraction of cases (approximately 1 in 10) the effect is neutralized by the back surface. The curvature of the back surface of the cornea is not considered in most studies, because it is more difficult to measure; moreover, in the case of severe corneal astigmatism, there is evidence that both surfaces have the same configuration. Noncorneal factors are errors in the curvature of the 2 surfaces of the crystalline lens, irregularity in the refractive index of the lens, and an eccentric lens position. Since the cornea is the dominant component of the eye's refracting system, a highly astigmatic cornea is likely to result in a similarly astigmatic ocular refraction (summary by Clementi et al., 1998).
Microphthalmia
MedGen UID:
10033
Concept ID:
C0026010
Congenital Abnormality
Microphthalmia is an eye abnormality that arises before birth. In this condition, one or both eyeballs are abnormally small. In some affected individuals, the eyeball may appear to be completely missing; however, even in these cases some remaining eye tissue is generally present. Such severe microphthalmia should be distinguished from another condition called anophthalmia, in which no eyeball forms at all. However, the terms anophthalmia and severe microphthalmia are often used interchangeably. Microphthalmia may or may not result in significant vision loss.\n\nPeople with microphthalmia may also have a condition called coloboma. Colobomas are missing pieces of tissue in structures that form the eye. They may appear as notches or gaps in the colored part of the eye called the iris; the retina, which is the specialized light-sensitive tissue that lines the back of the eye; the blood vessel layer under the retina called the choroid; or in the optic nerves, which carry information from the eyes to the brain. Colobomas may be present in one or both eyes and, depending on their size and location, can affect a person's vision.\n\nPeople with microphthalmia may also have other eye abnormalities, including clouding of the lens of the eye (cataract) and a narrowed opening of the eye (narrowed palpebral fissure). Additionally, affected individuals may have an abnormality called microcornea, in which the clear front covering of the eye (cornea) is small and abnormally curved.\n\nBetween one-third and one-half of affected individuals have microphthalmia as part of a syndrome that affects other organs and tissues in the body. These forms of the condition are described as syndromic. When microphthalmia occurs by itself, it is described as nonsyndromic or isolated.
Nystagmus
MedGen UID:
45166
Concept ID:
C0028738
Disease or Syndrome
Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.
Strabismus
MedGen UID:
21337
Concept ID:
C0038379
Disease or Syndrome
A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error.
Alternating esotropia
MedGen UID:
57515
Concept ID:
C0152205
Disease or Syndrome
Esotropia in which either eye may be used for fixation.
Reduced visual acuity
MedGen UID:
65889
Concept ID:
C0234632
Finding
Diminished clarity of vision.
Axenfeld anomaly
MedGen UID:
78611
Concept ID:
C0266548
Congenital Abnormality
Axenfeld's anomaly is a bilateral disorder characterized by a prominent, anteriorly displaced Schwalbe's line (posterior embryotoxon) and peripheral iris strands which span the anterior chamber angle to attach to Schwalbe's line.
Posterior embryotoxon
MedGen UID:
154282
Concept ID:
C0546967
Congenital Abnormality
A posterior embryotoxon is the presence of a prominent and anteriorly displaced line of Schwalbe.
Foveal hypoplasia
MedGen UID:
393047
Concept ID:
C2673946
Finding
Underdevelopment of the fovea centralis.
Foveal hyperpigmentation
MedGen UID:
815631
Concept ID:
C3809301
Finding
Increased amount of pigmentation in the fovea centralis.
Optic nerve misrouting
MedGen UID:
1615900
Concept ID:
C4531296
Anatomical Abnormality
Abnormal decussation of the visual pathways, typically identified using visual evoked potentials (VEP) (asymmetrical distribution of the VEP over the posterior scalp).

Recent clinical studies

Clinical prediction guides

Guardia A, Fernández A, Seruggia D, Chotard V, Sánchez-Castillo C, Kutsyr O, Sánchez-Sáez X, Zurita E, Cantero M, Rebsam A, Cuenca N, Montoliu L
Invest Ophthalmol Vis Sci 2023 Oct 3;64(13):32. doi: 10.1167/iovs.64.13.32. PMID: 37862028Free PMC Article
Weiner C, Hecht I, Rotenstreich Y, Guttman S, Or L, Morad Y, Shapira G, Shomron N, Pras E
Exp Eye Res 2020 Apr;193:107958. Epub 2020 Feb 4 doi: 10.1016/j.exer.2020.107958. PMID: 32032626
Al-Araimi M, Pal B, Poulter JA, van Genderen MM, Carr I, Cudrnak T, Brown L, Sheridan E, Mohamed MD, Bradbury J, Ali M, Inglehearn CF, Toomes C
Mol Vis 2013;19:2165-72. Epub 2013 Nov 1 PMID: 24194637Free PMC Article

Supplemental Content

Recent activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...