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Macrocephaly-intellectual disability-neurodevelopmental disorder-small thorax syndrome(SKS)

MedGen UID:
899689
Concept ID:
C4225259
Disease or Syndrome
Synonyms: MACROCEPHALY, SEIZURES, MENTAL RETARDATION, UMBILICAL HERNIA, AND FACIAL DYSMORPHISM; Smith-Kingsmore syndrome
SNOMED CT: MINDS syndrome (1187304005); Macrocephaly, intellectual disability, neurodevelopmental disorder, small thorax syndrome (1187304005); Smith Kingsmore syndrome (1187304005); MINDS (macrocephaly, intellectual disability, neurodevelopmental disorder, small thorax) syndrome (1187304005)
Modes of inheritance:
Autosomal dominant inheritance
MedGen UID:
141047
Concept ID:
C0443147
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 heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele.
 
Gene (location): MTOR (1p36.22)
 
Monarch Initiative: MONDO:0014716
OMIM®: 616638
Orphanet: ORPHA457485

Definition

Smith-Kingsmore syndrome (SKS) is a rare autosomal dominant syndromic intellectual disability syndrome characterized by macrocephaly, seizures, umbilical hernia, and facial dysmorphic features including frontal bossing, midface hypoplasia, small chin, hypertelorism with downslanting palpebral fissures, depressed nasal bridge, smooth philtrum, and thin upper lip (Smith et al., 2013; Baynam et al., 2015). [from OMIM]

Additional description

From MedlinePlus Genetics
Smith-Kingsmore syndrome is a neurological disorder characterized by a head that is larger than normal (macrocephaly), intellectual disability, and seizures. In some people with this condition, the ability to speak is delayed or never develops. Some children with Smith-Kingsmore syndrome have neurodevelopmental conditions known as attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder, which is characterized by impaired communication and social interaction. Structural brain abnormalities may also be present in affected individuals. For example, one or both sides of the brain may be enlarged (hemimegalencephaly or megalencephaly) or have too many ridges on the surface (polymicrogyria), or the fluid-filled spaces near the center of the brain (ventricles) may be bigger than normal (ventriculomegaly).

Many people with Smith-Kingsmore syndrome have unusual facial features, such as a triangular face with a pointed chin, a protruding forehead (frontal bossing), widely spaced eyes (hypertelorism) with outside corners that point downward (downslanting palpebral fissures), a flat nasal bridge, or a long space between the nose and upper lip (long philtrum). However, not everyone with Smith-Kingsmore syndrome has distinctive facial features.  https://medlineplus.gov/genetics/condition/smith-kingsmore-syndrome

Clinical features

From HPO
Cryptorchidism
MedGen UID:
8192
Concept ID:
C0010417
Congenital Abnormality
Cryptorchidism, or failure of testicular descent, is a common human congenital abnormality with a multifactorial etiology that likely reflects the involvement of endocrine, environmental, and hereditary factors. Cryptorchidism can result in infertility and increases risk for testicular tumors. Testicular descent from abdomen to scrotum occurs in 2 distinct phases: the transabdominal phase and the inguinoscrotal phase (summary by Gorlov et al., 2002).
Short distal phalanx of finger
MedGen UID:
326590
Concept ID:
C1839829
Finding
Short distance from the end of the finger to the most distal interphalangeal crease or the distal interphalangeal joint flexion point. That is, hypoplasia of one or more of the distal phalanx of finger.
Deep palmar crease
MedGen UID:
387849
Concept ID:
C1857539
Finding
Excessively deep creases of the palm.
Short proximal phalanx of finger
MedGen UID:
348659
Concept ID:
C1860606
Congenital Abnormality
Congenital hypoplasia of one or more proximal phalanx of finger.
Rhizomelia
MedGen UID:
357122
Concept ID:
C1866730
Congenital Abnormality
Disproportionate shortening of the proximal segment of limbs (i.e. the femur and humerus).
Large for gestational age
MedGen UID:
341215
Concept ID:
C1848395
Finding
The term large for gestational age applies to babies whose birth weight lies above the 90th percentile for that gestational age.
Feeding difficulties
MedGen UID:
65429
Concept ID:
C0232466
Finding
Impaired ability to eat related to problems gathering food and getting ready to suck, chew, or swallow it.
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.
Megalencephaly
MedGen UID:
65141
Concept ID:
C0221355
Congenital Abnormality
Diffuse enlargement of the entire cerebral hemispheres leading to macrocephaly (with or without overlying cortical dysplasia).
Hypoplasia of the corpus callosum
MedGen UID:
138005
Concept ID:
C0344482
Congenital Abnormality
Underdevelopment of the corpus callosum.
Hemimegalencephaly
MedGen UID:
140910
Concept ID:
C0431391
Finding
Enlargement of all or parts of one cerebral hemisphere.
Ventriculomegaly
MedGen UID:
480553
Concept ID:
C3278923
Finding
An increase in size of the ventricular system of the brain.
Perisylvian polymicrogyria
MedGen UID:
481305
Concept ID:
C3279675
Finding
Polymicrogyria (an excessive number of small gyri or convolutions) that is maximal in perisylvian regions (the regions that surround the Sylvian fissures), which may be symmetric or asymmetric and may extend beyond perisylvian regions. The Sylvian fissures often extend posteriorly and superiorly.
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.
Reduced cerebral white matter volume
MedGen UID:
1815057
Concept ID:
C5706151
Finding
An abnormally low volume of the white matter of the brain.
Thrombocytopenia
MedGen UID:
52737
Concept ID:
C0040034
Disease or Syndrome
A reduction in the number of circulating thrombocytes.
Umbilical hernia
MedGen UID:
9232
Concept ID:
C0019322
Anatomical Abnormality
Protrusion of abdominal contents through a defect in the abdominal wall musculature around the umbilicus. Skin and subcutaneous tissue overlie the defect.
Frontal bossing
MedGen UID:
67453
Concept ID:
C0221354
Congenital Abnormality
Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline.
Diastasis recti
MedGen UID:
113171
Concept ID:
C0221766
Disease or Syndrome
A separation of the rectus abdominis muscle into right and left halves (which are normally joined at the midline at the linea alba).
Thoracic hypoplasia
MedGen UID:
373339
Concept ID:
C1837482
Congenital Abnormality
Generalized hypotonia
MedGen UID:
346841
Concept ID:
C1858120
Finding
Generalized muscular hypotonia (abnormally low muscle tone).
Wide anterior fontanel
MedGen UID:
400926
Concept ID:
C1866134
Finding
Enlargement of the anterior fontanelle with respect to age-dependent norms.
Macrocephaly
MedGen UID:
745757
Concept ID:
C2243051
Finding
Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.
Decreased circulating IgA level
MedGen UID:
57934
Concept ID:
C0162538
Disease or Syndrome
Decreased levels of immunoglobulin A (IgA).
Hypoglycemia
MedGen UID:
6979
Concept ID:
C0020615
Disease or Syndrome
A decreased concentration of glucose in the blood.
Wide mouth
MedGen UID:
44238
Concept ID:
C0024433
Congenital Abnormality
Distance between the oral commissures more than 2 SD above the mean. Alternatively, an apparently increased width of the oral aperture (subjective).
High forehead
MedGen UID:
65991
Concept ID:
C0239676
Finding
An abnormally increased height of the forehead.
Open mouth
MedGen UID:
116104
Concept ID:
C0240379
Finding
A facial appearance characterized by a permanently or nearly permanently opened mouth.
Downslanted palpebral fissures
MedGen UID:
98391
Concept ID:
C0423110
Finding
The palpebral fissure inclination is more than two standard deviations below the mean.
Smooth philtrum
MedGen UID:
222980
Concept ID:
C1142533
Finding
Flat skin surface, with no ridge formation in the central region of the upper lip between the nasal base and upper vermilion border.
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.
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.
Short nose
MedGen UID:
343052
Concept ID:
C1854114
Finding
Distance from nasion to subnasale more than two standard deviations below the mean, or alternatively, an apparently decreased length from the nasal root to the nasal tip.
Long philtrum
MedGen UID:
351278
Concept ID:
C1865014
Finding
Distance between nasal base and midline upper lip vermilion border more than 2 SD above the mean. Alternatively, an apparently increased distance between nasal base and midline upper lip vermilion border.
Thin upper lip vermilion
MedGen UID:
355352
Concept ID:
C1865017
Finding
Height of the vermilion of the upper lip in the midline more than 2 SD below the mean. Alternatively, an apparently reduced height of the vermilion of the upper lip in the frontal view (subjective).
Short chin
MedGen UID:
784514
Concept ID:
C3697248
Finding
Decreased vertical distance from the vermilion border of the lower lip to the inferior-most point of the chin.
Cafe-au-lait spot
MedGen UID:
113157
Concept ID:
C0221263
Finding
Cafe-au-lait spots are hyperpigmented lesions that can vary in color from light brown to dark brown with smooth borders and having a size of 1.5 cm or more in adults and 0.5 cm or more in children.
Curly hair
MedGen UID:
488919
Concept ID:
C0558165
Finding
Deep plantar creases
MedGen UID:
341890
Concept ID:
C1857953
Finding
The presence of unusually deep creases (ridges/wrinkles) on the skin of sole of foot.
Hypertelorism
MedGen UID:
9373
Concept ID:
C0020534
Finding
Although hypertelorism means an excessive distance between any paired organs (e.g., the nipples), the use of the word has come to be confined to ocular hypertelorism. Hypertelorism occurs as an isolated feature and is also a feature of many syndromes, e.g., Opitz G syndrome (see 300000), Greig cephalopolysyndactyly (175700), and Noonan syndrome (163950) (summary by Cohen et al., 1995).
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.

Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVMacrocephaly-intellectual disability-neurodevelopmental disorder-small thorax syndrome

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