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Seizures-scoliosis-macrocephaly syndrome(SSMS)

MedGen UID:
909039
Concept ID:
C4225248
Disease or Syndrome
Synonyms: Seizures, scoliosis, and macrocephaly syndrome; SEIZURES, SCOLIOSIS, AND MACROCEPHALY/MICROCEPHALY SYNDROME
SNOMED CT: SSM (seizures, scoliosis, macrocephaly) syndrome (1187250005); Seizures, scoliosis, macrocephaly syndrome (1187250005)
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): EXT2 (11p11.2)
 
Monarch Initiative: MONDO:0014731
OMIM®: 616682
Orphanet: ORPHA466926

Definition

Seizures, scoliosis, and macrocephaly/microcephaly syndrome (SSMS) is an autosomal recessive neurodevelopmental disorder characterized by global developmental delay apparent from early infancy, impaired intellectual development, behavioral problems, poor or absent speech, seizures, dysmorphic facial features with macro- or microcephaly, and skeletal abnormalities, including scoliosis and delayed bone age. Other features may include hypotonia, gastrointestinal problems, and exostoses (summary by Gentile et al., 2019). [from OMIM]

Clinical features

From HPO
Encopresis
MedGen UID:
754509
Concept ID:
C2945606
Sign or Symptom
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).
Proteinuria
MedGen UID:
10976
Concept ID:
C0033687
Finding
Increased levels of protein in the urine.
Pes planus
MedGen UID:
42034
Concept ID:
C0016202
Anatomical Abnormality
A foot where the longitudinal arch of the foot is in contact with the ground or floor when the individual is standing; or, in a patient lying supine, a foot where the arch is in contact with the surface of a flat board pressed against the sole of the foot by the examiner with a pressure similar to that expected from weight bearing; or, the height of the arch is reduced.
Overlapping toe
MedGen UID:
182531
Concept ID:
C0920299
Anatomical Abnormality
Describes a foot digit resting on the dorsal surface of an adjacent digit when the foot is at rest. Initially clawing may be dynamic and only noticeable on walking. Over time the plantar plate tears, subluxation occurs at the metatarsophalangeal joint (MTPJ), and the deformity becomes permanent.
Clinodactyly of the 5th finger
MedGen UID:
340456
Concept ID:
C1850049
Congenital Abnormality
Clinodactyly refers to a bending or curvature of the fifth finger in the radial direction (i.e., towards the 4th finger).
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.
Ventricular septal defect
MedGen UID:
42366
Concept ID:
C0018818
Congenital Abnormality
A hole between the two bottom chambers (ventricles) of the heart. The defect is centered around the most superior aspect of the ventricular septum.
Cerebral hemorrhage
MedGen UID:
423648
Concept ID:
C2937358
Pathologic Function
Hemorrhage into the parenchyma of the brain.
Constipation
MedGen UID:
1101
Concept ID:
C0009806
Sign or Symptom
Infrequent or difficult evacuation of feces.
Volvulus
MedGen UID:
21892
Concept ID:
C0042961
Disease or Syndrome
Abnormal twisting of a portion of intestine around itself or around a stalk of mesentery tissue.
Intestinal malrotation
MedGen UID:
113153
Concept ID:
C0221210
Congenital Abnormality
An abnormality of the intestinal rotation and fixation that normally occurs during the development of the gut. This can lead to volvulus, or twisting of the intestine that causes obstruction and necrosis.
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.
Gastroesophageal reflux
MedGen UID:
1368658
Concept ID:
C4317146
Finding
A condition in which the stomach contents leak backwards from the stomach into the esophagus through the lower esophageal sphincter.
Intellectual disability, moderate
MedGen UID:
7680
Concept ID:
C0026351
Mental or Behavioral Dysfunction
Moderate mental retardation is defined as an intelligence quotient (IQ) in the range of 35-49.
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.
Sleep apnea
MedGen UID:
11458
Concept ID:
C0037315
Disease or Syndrome
An intermittent cessation of airflow at the mouth and nose during sleep is known as sleep apnea. Apneas that last at least 10 seconds are considered significant, but individuals with sleep apnea may experience apneas lasting from 20 seconds up to 2 or 3 minutes. Patients may have up to 15 events per hour of sleep.
Motor stereotypies
MedGen UID:
21318
Concept ID:
C0038271
Individual Behavior
Use of the same abnormal action in response to certain triggers or at random. They may be used as a way to regulate one's internal state but must otherwise have no apparent functional purpose.
Unsteady gait
MedGen UID:
68544
Concept ID:
C0231686
Finding
A shaky or wobbly manner of walking.
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.
Autistic behavior
MedGen UID:
163547
Concept ID:
C0856975
Mental or Behavioral Dysfunction
Persistent deficits in social interaction and communication and interaction as well as a markedly restricted repertoire of activity and interest as well as repetitive patterns of behavior.
Loss of ambulation
MedGen UID:
332305
Concept ID:
C1836843
Finding
Inability to walk in a person who previous had the ability to walk.
Poor speech
MedGen UID:
341172
Concept ID:
C1848207
Finding
Motor delay
MedGen UID:
381392
Concept ID:
C1854301
Finding
A type of Developmental delay characterized by a delay in acquiring motor skills.
Hypotonia
MedGen UID:
10133
Concept ID:
C0026827
Finding
Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.
Scoliosis
MedGen UID:
11348
Concept ID:
C0036439
Disease or Syndrome
The presence of an abnormal lateral curvature of the spine.
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.
Reduced bone mineral density
MedGen UID:
393152
Concept ID:
C2674432
Finding
A reduction of bone mineral density, that is, of the amount of matter per cubic centimeter of bones.
Hiatus hernia
MedGen UID:
483347
Concept ID:
C3489393
Acquired Abnormality
The presence of a hernia in which the upper part of the stomach, i.e., mainly the gastric cardia protrudes through the diaphragmatic esophageal hiatus.
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.
Coarse facial features
MedGen UID:
335284
Concept ID:
C1845847
Finding
Absence of fine and sharp appearance of brows, nose, lips, mouth, and chin, usually because of rounded and heavy features or thickened skin with or without thickening of subcutaneous and bony tissues.
Hypoplastic philtrum
MedGen UID:
341641
Concept ID:
C1856886
Finding
Underdevelopment of the philtrum.
Nail dysplasia
MedGen UID:
331737
Concept ID:
C1834405
Congenital Abnormality
The presence of developmental dysplasia of the nail.
Preauricular skin tag
MedGen UID:
395989
Concept ID:
C1860816
Finding
A rudimentary tag of skin often containing ear tissue including a core of cartilage and located just anterior to the auricle (outer part of the ear).
Sparse hair
MedGen UID:
1790211
Concept ID:
C5551005
Finding
Reduced density of hairs.
Precocious puberty
MedGen UID:
18752
Concept ID:
C0034013
Disease or Syndrome
The onset of secondary sexual characteristics before a normal age. Although it is difficult to define normal age ranges because of the marked variation with which puberty begins in normal children, precocious puberty can be defined as the onset of puberty before the age of 8 years in girls or 9 years in boys.
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  
  • CROGVSeizures-scoliosis-macrocephaly syndrome

Recent clinical studies

Clinical prediction guides

Gentile M, Agolini E, Cocciadiferro D, Ficarella R, Ponzi E, Bellacchio E, Antonucci MF, Novelli A
Clin Genet 2019 Jan;95(1):165-171. Epub 2018 Oct 24 doi: 10.1111/cge.13458. PMID: 30288735
Farhan SM, Wang J, Robinson JF, Prasad AN, Rupar CA, Siu VM; FORGE Canada Consortium, Hegele RA
J Med Genet 2015 Oct;52(10):666-75. Epub 2015 Aug 5 doi: 10.1136/jmedgenet-2015-103279. PMID: 26246518

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