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Knobloch syndrome 1(KNO1)

MedGen UID:
1642123
Concept ID:
C4551775
Disease or Syndrome
Synonyms: KNO1; Knobloch Syndrome Type I
 
Gene (location): COL18A1 (21q22.3)
 
Monarch Initiative: MONDO:0800167
OMIM®: 267750

Definition

Knobloch syndrome-1 (KNO1) is an autosomal recessive developmental disorder primarily characterized by typical eye abnormalities, including high myopia, cataracts, dislocated lens, vitreoretinal degeneration, and retinal detachment, with occipital skull defects, which can range from occipital encephalocele to occult cutis aplasia (summary by Aldahmesh et al., 2011). Genetic Heterogeneity of Knobloch Syndrome KNO2 (618458) is caused by mutation in the PAK2 gene (605022) on chromosome 3q29. [from OMIM]

Additional description

From MedlinePlus Genetics
Knobloch syndrome is a rare condition characterized by severe vision problems and a skull defect.

A characteristic feature of Knobloch syndrome is extreme nearsightedness (high myopia). In addition, several other eye abnormalities are common in people with this condition. Most affected individuals have vitreoretinal degeneration, which is breakdown (degeneration) of two structures in the eye called the vitreous and the retina. The vitreous is the gelatin-like substance that fills the eye, and the retina is the light-sensitive tissue at the back of the eye. Vitreoretinal degeneration often leads to separation of the retina from the back of the eye (retinal detachment). Affected individuals may also have abnormalities in the central area of the retina, called the macula. The macula is responsible for sharp central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. Due to abnormalities in the vitreous, retina, and macula, people with Knobloch syndrome often develop blindness in one or both eyes.

Another characteristic feature of Knobloch syndrome is a skull defect called an occipital encephalocele, which is a sac-like protrusion of the brain (encephalocele) through a defect in the bone at the base of the skull (occipital bone). Some affected individuals have been diagnosed with a different skull defect in the occipital region, and it is unclear whether the defect is always a true encephalocele. In other conditions, encephaloceles may be associated with intellectual disability; however, most people with Knobloch syndrome have normal intelligence.  https://medlineplus.gov/genetics/condition/knobloch-syndrome

Clinical features

From HPO
Hydronephrosis
MedGen UID:
42531
Concept ID:
C0020295
Disease or Syndrome
Severe distention of the kidney with dilation of the renal pelvis and calices.
Renal duplication
MedGen UID:
488826
Concept ID:
C0266298
Congenital Abnormality
A congenital anomaly of the urinary tract, in which the kidney is duplicated and is drained via two separate renal pelves and ureters.
Duplicated collecting system
MedGen UID:
346936
Concept ID:
C1858565
Anatomical Abnormality
A duplication of the collecting system of the kidney, defined as a kidney with two (instead of, normally, one) pyelocaliceal systems. The pyelocaliceal system is comprised of the renal pelvis and calices. The duplicated renal collecting system can be associated with a single ureter or with double ureters. In the latter case, the two ureters empty separately into the bladder or fuse to form a single ureteral orifice.
Bifid ureter
MedGen UID:
854360
Concept ID:
C3887498
Congenital Abnormality
Incomplete duplication of the ureter.
Patent ductus arteriosus
MedGen UID:
4415
Concept ID:
C0013274
Congenital Abnormality
In utero, the ductus arteriosus (DA) serves to divert ventricular output away from the lungs and toward the placenta by connecting the main pulmonary artery to the descending aorta. A patent ductus arteriosus (PDA) in the first 3 days of life is a physiologic shunt in healthy term and preterm newborn infants, and normally is substantially closed within about 24 hours after bith and completely closed after about three weeks. Failure of physiologcal closure is referred to a persistent or patent ductus arteriosus (PDA). Depending on the degree of left-to-right shunting, PDA can have clinical consequences.
Congenital hypertrophic pyloric stenosis
MedGen UID:
196010
Concept ID:
C0700639
Congenital Abnormality
Pyloric stenosis, also known as infantile hypertrophic pyloric stenosis, is an uncommon condition in infants characterized by abnormal thickening of the pylorus muscles in the stomach leading to gastric outlet obstruction. Clinically infants are well at birth. Then, at 3 to 6 weeks of age, the infants present with projectile vomiting, potentially leading to dehydration and weight loss.
Cerebellar ataxia
MedGen UID:
849
Concept ID:
C0007758
Disease or Syndrome
Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly).
Occipital encephalocele
MedGen UID:
4935
Concept ID:
C0014067
Congenital Abnormality
A type of encephalocele (that is, a a protrusion of part of the cranial contents including brain tissue through a congenital opening in the cranium, typically covered with skin or mucous membrane) in the occipital region of the skull. Occipital encephalocele presents as a midline swelling over the occipital bone. It is usually covered with normal full-thickness scalp.
Seizure
MedGen UID:
20693
Concept ID:
C0036572
Sign or Symptom
A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.
Spina bifida occulta
MedGen UID:
36380
Concept ID:
C0080174
Congenital Abnormality
The closed form of spina bifida with incomplete closure of a vertebral body with intact overlying skin.
Cerebral atrophy
MedGen UID:
116012
Concept ID:
C0235946
Disease or Syndrome
Atrophy (wasting, decrease in size of cells or tissue) affecting the cerebrum.
Polymicrogyria
MedGen UID:
78605
Concept ID:
C0266464
Congenital Abnormality
Polymicrogyria is a congenital malformation of the cerebral cortex characterized by abnormal cortical layering (lamination) and an excessive number of small gyri (folds).
Absent septum pellucidum
MedGen UID:
96561
Concept ID:
C0431371
Congenital Abnormality
Absence of the septum pellucidum (meaning translucent wall in Latin - SP), also known as the ventricle of Sylvius. The septum pellucidum is a thin, triangular double membrane separating the frontal horns of the right and left lateral ventricles of the brain. It extends between the anterior portion of the corpus callosum, and the body of the fornix and its width varies from 1.5 to 3.0 mm.
Global developmental delay
MedGen UID:
107838
Concept ID:
C0557874
Finding
A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.
Cerebellar atrophy
MedGen UID:
196624
Concept ID:
C0740279
Disease or Syndrome
Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.
Occipital meningocele
MedGen UID:
336389
Concept ID:
C1848652
Disease or Syndrome
A herniation of meninges through a congenital bone defect in the skull in the occipital region.
Ventriculomegaly
MedGen UID:
480553
Concept ID:
C3278923
Finding
An increase in size of the ventricular system of the brain.
Intellectual disability
MedGen UID:
811461
Concept ID:
C3714756
Mental or Behavioral Dysfunction
Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.
Myoclonic seizure
MedGen UID:
1385980
Concept ID:
C4317123
Sign or Symptom
A myoclonic seizure is a type of motor seizure characterized by sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus.
Joint hypermobility
MedGen UID:
336793
Concept ID:
C1844820
Finding
The capability that a joint (or a group of joints) has to move, passively and/or actively, beyond normal limits along physiological axes.
Microcephaly
MedGen UID:
1644158
Concept ID:
C4551563
Finding
Head circumference below 2 standard deviations below the mean for age and gender.
Bulbous nose
MedGen UID:
66013
Concept ID:
C0240543
Finding
Increased volume and globular shape of the anteroinferior aspect of the nose.
Telecanthus
MedGen UID:
140836
Concept ID:
C0423113
Finding
Distance between the inner canthi more than two standard deviations above the mean (objective); or, apparently increased distance between the inner canthi.
Alopecia of scalp
MedGen UID:
658454
Concept ID:
C0574769
Finding
Epicanthus
MedGen UID:
151862
Concept ID:
C0678230
Congenital Abnormality
Epicanthus is a condition in which a fold of skin stretches from the upper to the lower eyelid, partially covering the inner canthus. Usher (1935) noted that epicanthus is a normal finding in the fetus of all races. Epicanthus also occurs in association with hereditary ptosis (110100).
Depressed nasal bridge
MedGen UID:
373112
Concept ID:
C1836542
Finding
Posterior positioning of the nasal root in relation to the overall facial profile for age.
Prominent forehead
MedGen UID:
373291
Concept ID:
C1837260
Finding
Forward prominence of the entire forehead, due to protrusion of the frontal bone.
Narrow face
MedGen UID:
373334
Concept ID:
C1837463
Finding
Bizygomatic (upper face) and bigonial (lower face) width are both more than 2 standard deviations below the mean (objective); or, an apparent reduction in the width of the upper and lower face (subjective).
Narrow forehead
MedGen UID:
326956
Concept ID:
C1839758
Finding
Width of the forehead or distance between the frontotemporales is more than two standard deviations below the mean (objective); or apparently narrow intertemporal region (subjective).
Midface retrusion
MedGen UID:
339938
Concept ID:
C1853242
Anatomical Abnormality
Posterior positions and/or vertical shortening of the infraorbital and perialar regions, or increased concavity of the face and/or reduced nasolabial angle.
Horizontal eyebrow
MedGen UID:
478649
Concept ID:
C3277019
Finding
An eyebrow that extends straight across the brow, without curve.
Developmental cataract
MedGen UID:
3202
Concept ID:
C0009691
Congenital Abnormality
A cataract that occurs congenitally as the result of a developmental defect, in contrast to the majority of cataracts that occur in adulthood as the result of degenerative changes of the lens.
Glaucoma
MedGen UID:
42224
Concept ID:
C0017601
Disease or Syndrome
Glaucoma refers loss of retinal ganglion cells in a characteristic pattern of optic neuropathy usually associated with increased intraocular pressure.
Lens subluxation
MedGen UID:
9718
Concept ID:
C0023316
Disease or Syndrome
Partial dislocation of the lens of the eye.
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.
Retinal detachment
MedGen UID:
19759
Concept ID:
C0035305
Disease or Syndrome
Primary or spontaneous detachment of the retina occurs due to underlying ocular disease and often involves the vitreous as well as the retina. The precipitating event is formation of a retinal tear or hole, which permits fluid to accumulate under the sensory layers of the retina and creates an intraretinal cleavage that destroys the neurosensory process of visual reception. Vitreoretinal degeneration and tear formation are painless phenomena, and in most cases, significant vitreoretinal pathology is found only after detachment of the retina starts to cause loss of vision or visual field. Without surgical intervention, retinal detachment will almost inevitably lead to total blindness (summary by McNiel and McPherson, 1971).
Band-shaped keratopathy
MedGen UID:
56354
Concept ID:
C0155120
Disease or Syndrome
An abnormality of the cornea characterized by the deposition of calcium in a band across the central cornea, leading to decreased vision, foreign body sensation, and ocular irritation.
Phthisis bulbi
MedGen UID:
124382
Concept ID:
C0271007
Finding
Atrophy of the eyeball with blindness and decreased intraocular pressure due to end-stage intraocular disease.
Cortical cataract
MedGen UID:
82868
Concept ID:
C0271160
Acquired Abnormality
A cataract which affects the layer of the lens surrounding the nucleus, i.e., the lens cortex. It is identified by its unique wedge or spoke appearance.
High myopia
MedGen UID:
78759
Concept ID:
C0271183
Disease or Syndrome
A severe form of myopia with greater than -6.00 diopters.
Horizontal nystagmus
MedGen UID:
124399
Concept ID:
C0271385
Disease or Syndrome
Nystagmus consisting of horizontal to-and-fro eye movements.
Vitreoretinopathy
MedGen UID:
87480
Concept ID:
C0344290
Disease or Syndrome
Ocular abnormality characterized by premature degeneration of the vitreous and the retina that may be associated with increased risk of retinal detachment.
Persistent pupillary membrane
MedGen UID:
138009
Concept ID:
C0344541
Congenital Abnormality
The presence of remnants of a fetal membrane that persist as strands of tissue crossing the pupil.
Optic disc pallor
MedGen UID:
108218
Concept ID:
C0554970
Finding
A pale yellow discoloration of the optic disc (the area of the optic nerve head in the retina). The optic disc normally has a pinkish hue with a central yellowish depression.
Iris transillumination defect
MedGen UID:
786045
Concept ID:
C1096099
Anatomical Abnormality
Transmission of light through the iris as visualized upon slit lamp examination or infrared iris transillumination videography. The light passes through defects in the pigmentation of the iris.
Peripapillary atrophy
MedGen UID:
473480
Concept ID:
C1719838
Pathologic Function
Thinning in the layers of the retina and retinal pigment epithelium around the optic nerve.
Macular hypoplasia
MedGen UID:
340322
Concept ID:
C1849412
Finding
Underdevelopment of the macula lutea.
Attenuation of retinal blood vessels
MedGen UID:
480605
Concept ID:
C3278975
Finding
Visual impairment
MedGen UID:
777085
Concept ID:
C3665347
Finding
Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.
Slow pupillary light response
MedGen UID:
868184
Concept ID:
C4022576
Finding
Reduced velocity and acceleration in the pupillary light response.
Chorioretinal atrophy
MedGen UID:
884881
Concept ID:
C4048273
Disease or Syndrome
Atrophy of the choroid and retinal layers of the fundus.
Gaze-evoked nystagmus
MedGen UID:
1808161
Concept ID:
C5574666
Disease or Syndrome
Nystagmus made apparent by looking to the right or to the left.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  

Recent clinical studies

Diagnosis

Vasilyeva T, Kadyshev V, Khalanskaya O, Kuznetsova S, Ionova S, Marakhonov A, Zinchenko R
Genes (Basel) 2024 Oct 1;15(10) doi: 10.3390/genes15101295. PMID: 39457419Free PMC Article

Clinical prediction guides

Vasilyeva T, Kadyshev V, Khalanskaya O, Kuznetsova S, Ionova S, Marakhonov A, Zinchenko R
Genes (Basel) 2024 Oct 1;15(10) doi: 10.3390/genes15101295. PMID: 39457419Free PMC Article

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