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Genetic counseling: Hypotonia - Developmental Delay

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Hypotonia - Developmental Delay


  • Introductions, acknowledge prior contact
  • Assess main concerns of patient
  • Why are they visiting Genetics today?
    • What do they hope to gain from the session?
      • explore desire to have a diagnosis
        • mother previously mentioned that they had come to terms with not having a diagnosis
  • Overview of today's session
    • Restate patient's concerns
    • Medical history, family history, physical exam, genetics, recurrence risk, testing options and limitations

Pediatric IntakeEdit

  • Family History
    • any relatives with hypotonia? developmental delay or learning disabilities? MR? -- no to all
    • history of infant deaths or miscarriages? birth defects? -- no
    • diabetes? cancer? thyroid prolems? heart problems? respiratory problems? genetic conditions? -- no to all
    • consanguinity? -- no

Differential DiagnosisEdit

  • Canavan disease
    • autosomal recessive
    • characterized by developmental delays by age 3-5 months, severe hypotonia involving "head lag", and inability to sit, walk, or speak
    • hypotonia eventually changes to spasticity and help with feeding is necessary
    • macrocephaly
    • Testing
      • urine analysis for concentration of N-acetylaspartic acid (NAA)
        • increased in affected patients
      • blood analysis for levels of aspartoacylase enzymatic activity
        • often unmeasurable in affected patients

Myotonic DystrophyEdit

    • autosomal dominant
    • incidence of 1/20,000
    • suspected in infants with hypotonia, facial muscle weakness, generalized weakness, club foot, and respiratory insufficiency or failure
    • Mild -- characterized by cataract and mild myotonia
    • Classic -- characterized by muscle weakness and wasting, cataracts, myotonia, cardiac conduction abnormalities
    • Congenital -- hypotonia, severe generalized weakness at birth, often have respiratory problems and early death, MR common
    • Testing
      • DNA analysis is 100% sensitive
        • detects an expansion of the CTG trinucleotide repeat in the DMPK gene (19q13)
      • > 37 repeats is abnormal
      • > 50 repeats are symptomatic
      • > 1000 repeats often seen in congenital type
  • Cerebellar Ataxia
    • most types have onset in adulthood
    • Spinocerebellar Ataxia 7 -- failure to thrive and loss of motor milestones, loss of vision
    • Spinocerebellar Ataxia 8 -- common initial symptoms are scanning dysarthria with a characteristic drawn-out slowness of speech and gait instability, hyperactive tendon reflexes
      • onset can be as early as one year old
      • Testing -- CTA/CTG expansion in the SCA8 gene (13q21) can be detected via DNA analysis
  • Aicardi syndrome
    • X-linked dominant inheritance
    • characterized by the partial or complete absence of the corpus callosum (the structure that links the 2 hemispheres of the brain), infantile spasms, mental retardation, and an ocular abnormality called lacunae (lesions) of the retina of the eyes
    • may be associated with other brain defects such as microcephaly or porencephalic cysts (cerebrospinal fluid-filled cavities or gaps in the brain)
    • onset generally begins between the ages of 3 and 5 months
  • Myasthenia gravis (familial infantile)
    • autosomal recessive
    • characterized by respiratory and feeding difficulties in an infant
    • absence or weakness of the ocular muscles is also characteristic
  • Familial Dysautonomia
    • characteristics include lack of tearing, emotional lability, paroxysmal hypertension, increased sweating, cold hands and feet, corneal anesthesia, erythematous blotching of the skin, and drooling
    • the absence of the fungiform papillae of the tongue is also characteristic
    • scoliosis is often severe and neuropathic joints of the Charcot type may develop
    • Ashkenazi-Jewish heritage is common

Previous TestingEdit

  • chromosomal testing done previously -- results normal

Management and TreatmentEdit

Psychosocial IssuesEdit

    • How important is a diagnosis to you?
    • If the visit to Genetics does not result in a diagnosis, what will this mean to you?
    • Are you worried about your child having a "label"?
  • Financial concerns
  • Support Network
    • do attend meeting of "Mother of Special Children" each month
    • support from family? friends? church?
  • Educational concerns

Support Groups and ResourcesEdit

  • Mothers of Special Children
meet the second Monday of each month at 7:30
Hyde Park Bethlehem United Church
Hyde Park and Madison Road
  • Ohio Coalition for the Education of Children with Disabilities
Director: Margaret Burley
Co-Director: Lee Ann Derugen
Executive Office
165 West Center Street, Suite 302
Marion, OH 43302-3741
Phone (740) 382-5452 or (800) 374-2806 (in Ohio)
Fax (740) 383-6421
  • March of Dimes Birth Defects Foundation
1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: 914-428-7100 888-MODIMES (663-4637)
Fax: 914-428-8203


  • (Canavan syndrome, Myotonic Dystrophy, Cerebellar Ataxia)
  • Smith's Recognizable Patterns of Human Malformation
  • OMIM #304050 (Aicardi syndrome), #254210 (Myasthenia gravis), #223900 (Familial Dysautonomia)
  • National Institute of Neurological Disorders and Stroke
    • Aicardi syndrome information page


The information in this outline was last updated in 2002.

This material has been imported fom the wikibook "Genetic counseling"[] under the GNU Free Documentation License.

Heckert GNU white Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License."

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