SnyderâRobinson syndrome | |
---|---|
Other names | Spermine synthase deficiency |
Specialty |
Medical genetics
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Symptoms | Intellectual disability, facial asymmetry, kyphoscoliosis, osteoporosis, hypotonia, asthenic build, seizures |
Usual onset | Adolescence, childhood, infancy |
Causes | Genetic [1] |
Differential diagnosis | Glycerol kinase deficiency, Urban syndrome, Rett syndrome, cerebral palsy, PraderâWilli syndrome |
Frequency | <1 per 1,000,000 |
SnyderâRobinson syndrome (SRS) is an extremely rare inherited genetic disorder [1] characterized by muscular and skeletal abnormalities, varying degrees of intellectual disability, seizures, [2] and slow development. [3]
SRS is caused by a mutated SMS gene at chromosome Xp21.3-p22.12, which carries instructions for producing the enzyme spermine synthase. [4] Spermine synthase in turn helps the body produce spermine, a polyamine critical to cell processes such as cell division, tissue repair, and apoptosis. [5] The resulting shortage of spermine in cells causes problems with development and brain function, though the exact mechanism is not understood.
The syndrome has also been referred to as SnyderâRobinson X-linked mental retardation syndrome (MRXSSR) and spermine synthase deficiency. SRS exclusively affects males. [1] Only about ten families currently have a child with SRS, and 50 people have been diagnosed worldwide since 1969. [6]
SnyderâRobinson usually is noticeable in infants, causing hypotonia and declining muscle tone with age. Seizures can occur in childhood, and children are especially susceptible to broken bones. [3]
During early childhood, SRS causes mild to profound intellectual disability; speech difficulties; problems with walking; osteoporosis; marfanoid habitus; and scoliosis, kyphosis, or both ( kyphoscoliosis). Distinctive facial features include a cleft palate, facial asymmetry, and a prominent lower lip. Kidney problems may also occur, such as nephrocalcinosis and renal cysts.[ citation needed]
Other symptoms that frequently appear in patients with Snyder-Robinson syndrome include arachnodactyly, decreased muscle mass, disproportionately tall stature, long and narrow face, nasal speech, slender toe, and thick lower lip vermilion. [7]
SRS is a recessive X-linked condition. [8] There are no known female cases, as both copies of the X chromosome would need to be mutated.[ citation needed]
When SRS is suspected, doctors will order a molecular genetic test to confirm a mutation in the SMS geneâspecifically a " hemizygous loss-of-function... pathogenic variant". However, there are currently no formal criteria for a diagnosis. [3]
Individuals with SnyderâRobinson may be assisted by occupational therapy, physical or speech therapy. Anti-seizure medications such as carbamazepine, phenobarbital, and clobazam can be used to manage seizures [2]âthe medication used often is influenced by the type of seizure. Bone density can be determined via a DXA scan and may be improved with calcium supplements. [3]
In 2014, several parents of individuals with SRS founded the SnyderâRobinson Foundation, a 501(c)(3) non-profit based in the US. [9] [6] It is a member of the National Organization for Rare Disorders. [10]
SRS was first reported in a 1969 paper published in Clinical Pediatrics by Russell D. Snyder [11] and Arthur Robinson, who described the syndrome as "recessive sex-linked mental retardation in the absence of other recognizable abnormalities". [12]
SnyderâRobinson syndrome | |
---|---|
Other names | Spermine synthase deficiency |
Specialty |
Medical genetics
![]() |
Symptoms | Intellectual disability, facial asymmetry, kyphoscoliosis, osteoporosis, hypotonia, asthenic build, seizures |
Usual onset | Adolescence, childhood, infancy |
Causes | Genetic [1] |
Differential diagnosis | Glycerol kinase deficiency, Urban syndrome, Rett syndrome, cerebral palsy, PraderâWilli syndrome |
Frequency | <1 per 1,000,000 |
SnyderâRobinson syndrome (SRS) is an extremely rare inherited genetic disorder [1] characterized by muscular and skeletal abnormalities, varying degrees of intellectual disability, seizures, [2] and slow development. [3]
SRS is caused by a mutated SMS gene at chromosome Xp21.3-p22.12, which carries instructions for producing the enzyme spermine synthase. [4] Spermine synthase in turn helps the body produce spermine, a polyamine critical to cell processes such as cell division, tissue repair, and apoptosis. [5] The resulting shortage of spermine in cells causes problems with development and brain function, though the exact mechanism is not understood.
The syndrome has also been referred to as SnyderâRobinson X-linked mental retardation syndrome (MRXSSR) and spermine synthase deficiency. SRS exclusively affects males. [1] Only about ten families currently have a child with SRS, and 50 people have been diagnosed worldwide since 1969. [6]
SnyderâRobinson usually is noticeable in infants, causing hypotonia and declining muscle tone with age. Seizures can occur in childhood, and children are especially susceptible to broken bones. [3]
During early childhood, SRS causes mild to profound intellectual disability; speech difficulties; problems with walking; osteoporosis; marfanoid habitus; and scoliosis, kyphosis, or both ( kyphoscoliosis). Distinctive facial features include a cleft palate, facial asymmetry, and a prominent lower lip. Kidney problems may also occur, such as nephrocalcinosis and renal cysts.[ citation needed]
Other symptoms that frequently appear in patients with Snyder-Robinson syndrome include arachnodactyly, decreased muscle mass, disproportionately tall stature, long and narrow face, nasal speech, slender toe, and thick lower lip vermilion. [7]
SRS is a recessive X-linked condition. [8] There are no known female cases, as both copies of the X chromosome would need to be mutated.[ citation needed]
When SRS is suspected, doctors will order a molecular genetic test to confirm a mutation in the SMS geneâspecifically a " hemizygous loss-of-function... pathogenic variant". However, there are currently no formal criteria for a diagnosis. [3]
Individuals with SnyderâRobinson may be assisted by occupational therapy, physical or speech therapy. Anti-seizure medications such as carbamazepine, phenobarbital, and clobazam can be used to manage seizures [2]âthe medication used often is influenced by the type of seizure. Bone density can be determined via a DXA scan and may be improved with calcium supplements. [3]
In 2014, several parents of individuals with SRS founded the SnyderâRobinson Foundation, a 501(c)(3) non-profit based in the US. [9] [6] It is a member of the National Organization for Rare Disorders. [10]
SRS was first reported in a 1969 paper published in Clinical Pediatrics by Russell D. Snyder [11] and Arthur Robinson, who described the syndrome as "recessive sex-linked mental retardation in the absence of other recognizable abnormalities". [12]