Syndromic Growth Disorders and Short Stature
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Questions and Answers

What is a syndrome?

  • A group of signs and symptoms that occur together and characterize a particular abnormality or condition (correct)
  • A type of chromosomal disorder
  • A pattern of diagnosis based on cause and effect
  • A condition that affects only the skeletal system

    • What is the most common chromosomal cause of short stature?

  • Turner syndrome
  • Down syndrome (correct)
  • Klinefelter syndrome
  • Noonan syndrome

    • What is the genetic defect in Turner syndrome?

  • Absence of one X chromosome or a chromosome with a short arm (correct)
  • Mutations in genes in the RAS-MAPK pathway
  • Mutation in the FGFR3 gene
  • Presence of an extra X chromosome

    • What is the name of the gene responsible for achondroplasia?

    <p>FGFR3</p> Signup and view all the answers

    What is the effect of vosoritide on achondroplasia?

    <p>It has a positive effect on growth and possibly on spinal stenosis</p> Signup and view all the answers

    What is the definition of tall stature?

    <p>Height &gt; 2 SDS</p> Signup and view all the answers

    What is the name of the receptor affected in achondroplasia?

    <p>Fibroblast growth factor receptor 3</p> Signup and view all the answers

    What is the difference between syndromic and non-syndromic growth disorders?

    <p>Syndromic disorders have multiple symptoms, non-syndromic have only short stature</p> Signup and view all the answers

    What is the definition of short stature?

    <p>Height &gt; 1.6 SDS under target height</p> Signup and view all the answers

    What is the effect of a mutation in the FGFR3 gene?

    <p>Constant growth inhibition</p> Signup and view all the answers

    What is the mechanism of action of vosoritide in the treatment of achondroplasia?

    <p>It inhibits the inhibiting effect of the FGFR3 receptor</p> Signup and view all the answers

    What is the risk of a child having achondroplasia if one parent has the condition?

    <p>50%</p> Signup and view all the answers

    What is the characteristic feature of Leri-Weil dyschondrosteosis?

    <p>Short arms and legs, with muscle hypertrophy</p> Signup and view all the answers

    What is the location of the SHOX gene, which is mutated in Leri-Weil dyschondrosteosis?

    <p>Pseudo-autosomal region of X and Y chromosomes</p> Signup and view all the answers

    What is the key feature of syndromic growth disorders?

    <p>Short stature with additional clinical features</p> Signup and view all the answers

    What is the importance of DNA analysis in making a diagnosis of syndromic growth disorders?

    <p>It is not always necessary</p> Signup and view all the answers

    What is the definition of short stature?

    <p>Height below 3 SD</p> Signup and view all the answers

    What is the inheritance pattern of achondroplasia?

    <p>Autosomal dominant</p> Signup and view all the answers

    Study Notes

    Tall Stature

    • Tall stature is defined as a height > 2 SDS (standard deviation) or > 1.6 SDS above target height based on parent's height
    • Tall stature differs from overgrowth, which refers to excessive growth in specific areas of the body

    Short Stature

    • Short stature is defined as a height < -2 SDS or > 1.6 SDS under target height based on parent's height
    • Height is measured in standing position, while length is measured in a lying down position, typically for newborns
    • Short stature can be classified into syndromic and non-syndromic growth disorders

    Measuring Guidelines

    • Measure patients' heights, weights, head circumference, armspan, and sitting height
    • Measure parents' heights, armspan, and sitting height when necessary
    • Height is influenced by 60-80% genetic factors, with feeding, health, and medication also playing important roles

    Syndrome Definition

    • A syndrome is a group of signs and symptoms that occur together and characterize a particular abnormality or condition
    • Syndrome identification involves pattern recognition
    • There are 1568 syndromes with short stature, and 320 syndromes with short stature and disproportion

    Causes of Short Stature

    • Primary growth disorders: syndromes, SGA (small for gestational age) without catch-up growth, skeletal dysplasia, and disorders of bone metabolism
    • Secondary growth disorders: malnutrition, celiac disease, hormonal disorders, and metabolic disorders
    • Idiopathic short stature, where the cause is unknown

    Turner Syndrome

    • Occurs only in girls, with a frequency of 1:2,500
    • Characterized by a missing or partially deleted X chromosome
    • Symptoms: short stature, heart condition, infertility, and may benefit from growth hormone therapy

    Noonan Syndrome

    • Caused by a gene mutation, occurring in both boys and girls
    • Symptoms: short stature, developmental delay, facial features (hypertelorism, ptosis, low-set ears, broad neck), congenital cardiac anomaly, pectus deformity, lymphatic abnormalities, coagulation defect, and cryptorchidism
    • Genetic mutations occur in the RAS-MAPK pathway, with PTPN11 being the most common mutation (50%)
    • May benefit from growth hormone therapy

    Skeletal Dysplasia

    • Frequency: 1:3,000 live births, and 1:110 perinatal mortality
    • Characterized by abnormalities in epiphysis, metaphysis, and/or diaphysis
    • Often causes disproportionate short stature
    • Heterogeneity in clinical and genetic features

    Achondroplasia

    • Frequency: 1:15,000 to 1:40,000
    • Clinical features: short stature, large head, short arms and legs, skin creases, pronounced lumbar lordosis, deep nasal bridge, frontal bossing, and short hands with trident
    • X-ray features: narrowed interpedicular distance in the lumbar spine
    • Treatment: symptomatic, with growth hormone not effective; limb lengthening and decompression spinal stenosis may be considered
    • Vosoritide is a novel treatment that has a positive effect on growth and possibly spinal stenosis

    FGFR3 Gene

    • Located on chromosome 4, mutations cause achondroplasia
    • Mutations are usually de novo, with a 50% chance of inheritance if one parent is affected
    • Genotype-phenotype correlation: autosomal dominant inheritance

    Leri-Weil Dyschondrosteosis (LWD)

    • Frequency: unknown
    • Clinical features: short stature, short arms and legs, Madelung deformity, muscle hypertrophy, and short 4th metacarpal bone
    • Growth hormone therapy is effective
    • Genetics: mutations in the SHOX gene, located in the pseudo-autosomal region 1

    Importance of Recognition

    • Recognition of syndromic growth disorder is crucial for diagnosis and management
    • Measurement and description of clinical features are essential for diagnosis
    • DNA analysis is not always necessary for diagnosis
    • Understanding the inheritance pattern is important for patient and family counseling

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    Description

    This quiz assesses your understanding of syndromic and non-syndromic growth disorders, specifically short stature, and their clinical features, molecular background, and inheritance patterns.

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