Congenital Myotonic and Congential Muscular Dytrophy are separate and disctinct disease. However, some of the symtoms that the patients have are similiar and so we include some limited information about this condition on our site.

• Fukuyama Type
• Occidental "Pure" Type

Types of CMD-From Recent workshop (1999)

The term Congenital muscular dystrophy has been used widely for a group of infants presenting with muscle weakness at birth or certainly within the first few months of life in association with a dystrophic pattern on muscle biopsy. There is often associated hypotonia on clinical presentation but other cases may present with arthrogryposis and associated contractures of the joints. The condition tends to remain static but some cases may show slow progression. Others, however, may have actual functional improvement, pass various motor milestones and achieve the ability to walk. There may be variable respiratory and swallowing problems at the time of presentation and associated diaphramgmatic involvement may lead to respiratory failure in later childhood or adolescence.

These are the types of Congenital Muscular Dystrophy

1.Congenital Muscular Dystrophy    

    A. Congenital Myotonic Dystrophy
            1. Pure 
                A. Merosin Positive
                B. Merosin Negative
             2. Fukuyama (Subdivided into types 1-4) 
                A. Classical (Type I)
                B. CMyD    (Type II)
                C. Atypical Fukuyama (Type III)
                D. Atypical Fukuyama (Type IV)

       C. Walker-Warburg Syndrome

This information on Types was taken from V. Du bowitz publishing of preliminary information of a workshop conducted on CMD in Europe in the Spring of 1999. More information on the congenital form is available on the page on Congenital Muscular Dystrophy Four phenotypes have been identified by the Recent ENMC Workshop. Click here for list of diagnostic criteria

1. "Pure" Congenital Muscular Dystrophy
2. Fukuyama type CMD
3. Muscle Eye Brain Disease
4. Walker Warburg Syndrome

Other classifications have been used in the past as well:

There are two categories of Congenital Myotonic Dystrophy that have been identified (Kobayashi). The classic form is call Occidental. This occidental type has no apparent Central Nervous System (CNS) involvement. this type can be further classified into Merosin Positive and Merosin Negative forms. The second type is called Fukuyama and (FCMD) This type has significant manifestations in the Central Nervous System area.

Fukuyama Type: FCMD is a distinct clinical entity characterized by early onset of muscle weakness, striking mental retardation, unusual brain anomalies, severe dystrophic muscle changes from early infancy. Recent Studies show that the FCMD is linked to Chromosome 9Q31-33

This type can be subdivided into 4 other types according to Dr. Fukuyama (Brain and Development Vol.  3 No 1, 1981) Congenital Progressive Muscular Dystrophy of the Fukuyama Type

Type I  Typical FCMD

This type is full described in the above paper and below on technical information. Documented cases have occurred only in Japan.

Type II

Quite distinct  from  Type I above with  no mental retardation is present. Serious muscle weakness and inability to walk independently. No pseudohypertrophy whatsoever

Type III

Mental retardation present but no as severe in type I, Only slight muscle weakness and has the ability to walk. No pseudohypertrophy

Type IV

Mental Retardation is slight, only slight muscle weakness and the ability to walk, pseudohypertrophy is prominent and widespread, Higher creatine kinase (CK) activity.

Technical Information on Fukuyama Type

FUKUYAMA-TYPE CONGENITAL MUSCULAR DYSTROPHY (FCMD) is the most common autosomal recessive disorder in Japan with an incidence of 0.7-1.2/100,000 births. It’s characterized by congenital muscular dystrophy associated with brain abnormalities. Researchers have mapped the FCMD gene to a region on chr 9q31, where it was found that insertion of a repeating DNA sequence has occurred in the gene. This insertion was seen in 87 percent of FCMD patients tested. This DNA sequence is about 3kb long and is inserted into the 3’ untranslated region of the gene. The normal gene was found to encode for a 461 amino acid containing protein that has never been reported before and appears to be a secreted protein, a protein that is actively released from the cell into extra cellular space. 

This gene is normally expressed in various tissues in individuals but isn’t found in  FCMD patients who have the DNA insertion into the gene. Researchers have named this new protein produced by the FCMD gene, fukutin. It’s interesting to note that a nearly identical DNA sequence to that of the insertion is found in the human gene encoding complement component 2 near the region of the Huntington’s disease gene.

Data suggest that fukutin protein may be located in the extracellular matrix after secretion from the cell, where it may interact with components of the extracellular matrix. Some extracellular components are known to participate in the complex that anchors muscle cells for contraction. CLASSICAL TYPE CONGENITAL MUSCULAR DYSTROPHY (CCMD) is linked to the absence of one of these extracellular matrix components, merosin. Thus, lack of fukutin in FCMD may cause this form of dystrophy by a mechanism not yet understood.

Another diagnostic feature of FCMD is micropolygyria (type II lissencephaly), in which migration of neurons during brain development is abnormal and the normal six-layered appearance of brain tissue doesn’t form. At least four genes are known to contribute to such disorders of brain development. Of these four, one gene produces reelin, also a secreted glycoprotein with features of extracellular proteins, as does fukutin. (Kobayashi, K., et al. An ancient retrotransposal insertion causes Fukuyama-type congenital muscular dystrophy. Letters to Nature. Nature. 394:388-392:1998.)

Occidental Type or "Pure" form :
Generally considered the milder form of CMD. It has no apparent Central Nervous System Involvement. It can be further divided into to other forms

MN-CMD
Merosin Negative form has uniform clinical features with marked muscle weakness and a delay in motor milestones, normal intelligence, relative high CK levels and white matter lucency on CT and MRI

MP-CMD
Merosin Positive Form is a group of heterogeneous disorders with approximately 10% of patients having severe symptoms

Throughout this page much of the information is presented for just one type CMD. This more recent information has not made its way into books or written print. Thus, some information you will have to interpret yourself to see if the information would apply to the Occidental or Fukuyama Types.

Prenatal Diagnosis:

Two groups of researchers have contributed to development of prenatal diagnosis for CONGENITAL MUSCULAR DYSTROPHY (CMD), classical form with merosin deficiency.
One group has concluded that a combination of immunocytochemistry (to detect presence of the merosin protein) and linkage analysis can be used for the prenatal diagnosis of merosin protein deficient CMD. The results are easy to interpret in families with total absence of the
protein, while caution is required when dealing with families where partial expression occurs. (Naom, I., et al. Prenatal diagnosis in merosin-deficient congenital muscular dystrophy. Neuromuscular Disorders. 7:176-179:1997.)

The second group reports the first prenatal diagnosis performed by direct mutation analysis. The reliability of prenatal diagnosis by microsatellite (DNA) analysis is dependent on the cause of the disease to be mapped to only one chromosome location and thus one gene. In families with a child having complete merosin deficiency, microsatellite analysis can be used for prenatal diagnosis with or without a direct assessment of the laminin alpha2 chain protein (the gene product) in fetal chorionic villous biopsies (CVS). In contrast, partial laminin alpha2 chain protein deficiency is heterogeneous (can be due to different causes). Merosin (laminin alpha2) gene maps to chromosome 6q. It is important to detect the laminin alpha2 chain (merosin) gene defects causing partial laminin alpha2 chain deficiency in order to perform prenatal diagnosis by direct mutation analysis. It is also essential to identify the other possible gene defects which may also induce secondary partial laminin alpha2 chain deficiency which occurs in FUKUYAMA CMD linked to chromosome 9q31-32. (Guicheney, P., et al. Genetics of laminin (2 chain (merosin) deficient congenital muscular dystrophy: from identification of mutations to prenatal diagnosis. Neuromuscular Disorders 7:180-186:1997.)For a complete and very through knowledge on this subject see Peter S. Harper's book Myotonic DystrophyClinical information on 50 patients with Merosin Positive CMD (MP-CMD) (Kobayashi) Note that this data applies only to the MP-CMD type of Muscular Dystrophy.

14% mothers had decreased Fetal Movement
54% of infants were noted abnormal at birth
30%Were considered Floppy
42% Had poor Suck.
16% had respiratory Difficulty
86% had delayed developmental Milestones
Head Control Delayed (Average 5 months)
Roll Over delayed (Average 9.5 Months)
Sit Alone delayed (10.8 months Average)
stand with support (19.0 Months Average)
Walk Alone (23.9 Months Average)
92% walked after 4 years
6% Lost this ability at age (6,9,10,14,19 and 23 years)
None began to walk after age of 4 years
55% showed Mild Facial Weakness
54% Joint contractures primarily in knees and ankles
32% Had hip joint contractures
32% Spine Deformity
26% had a high arched palate
IQ Four Patients under 80 IQ all the rest had no evidence of Mental Retardation