Overview
X-linked myotubular myopathy-abnormal genitalia syndrome is an extremely rare genetic condition that combines two main groups of problems: severe muscle weakness (myotubular myopathy) and abnormal development of the genitalia. This condition is caused by changes on the X chromosome, meaning it primarily affects males. Myotubular myopathy causes profound muscle weakness that is usually present from birth. Babies with this condition often have very low muscle tone (sometimes called 'floppy baby'), difficulty breathing on their own, trouble feeding, and delayed motor milestones. The muscle weakness can be life-threatening, especially in the newborn period, because of breathing difficulties. The abnormal genitalia component means that affected boys may have underdeveloped or ambiguous genitalia, which can complicate sex assignment and may require evaluation by endocrine and surgical specialists. The ICD-10 code Q99.8 places this condition among other specified chromosome abnormalities, suggesting that some cases may involve chromosomal rearrangements or deletions affecting the X chromosome. Treatment is currently supportive, focusing on respiratory care, feeding support, physical therapy, and management of genital abnormalities. There is no cure at this time, though gene therapy research for myotubular myopathy is an active area of investigation. A multidisciplinary team approach is essential for managing the complex needs of affected individuals.
Also known as:
Key symptoms:
Severe muscle weakness from birthVery low muscle tone (floppy baby)Difficulty breathing without supportTrouble feeding or swallowingAbnormal or underdeveloped genitaliaAmbiguous genitaliaDelayed motor milestonesThin or weak facial musclesLong face with a high-arched palateUndescended testesPoor head controlReduced or absent reflexesFrequent respiratory infectionsNeed for ventilator support
Clinical phenotype terms (15)— hover any for plain English
X-linked recessive
Carried on the X chromosome; typically affects males more than females
Neonatal
Begins at or shortly after birth (first 4 weeks)
Treatments
No FDA-approved treatments are currently listed for X-linked myotubular myopathy-abnormal genitalia syndrome.
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Specialists
View all specialists →No specialists are currently listed for X-linked myotubular myopathy-abnormal genitalia syndrome.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to X-linked myotubular myopathy-abnormal genitalia syndrome.
Community
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Caregiver Resources
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Questions for your doctor
Bring these to your next appointment
- Q1.What is the specific genetic change causing my child's condition, and does it involve a larger chromosomal deletion?,What level of respiratory support will my child need, and could this change over time?,What are the options for managing my child's genital abnormalities?,Are there any clinical trials or gene therapy studies my child might be eligible for?,What is the expected course of this condition, and what milestones might my child achieve?,How should we prepare for respiratory emergencies at home?,What support services and early intervention programs are available for our family?
Common questions about X-linked myotubular myopathy-abnormal genitalia syndrome
What is X-linked myotubular myopathy-abnormal genitalia syndrome?
X-linked myotubular myopathy-abnormal genitalia syndrome is an extremely rare genetic condition that combines two main groups of problems: severe muscle weakness (myotubular myopathy) and abnormal development of the genitalia. This condition is caused by changes on the X chromosome, meaning it primarily affects males. Myotubular myopathy causes profound muscle weakness that is usually present from birth. Babies with this condition often have very low muscle tone (sometimes called 'floppy baby'), difficulty breathing on their own, trouble feeding, and delayed motor milestones. The muscle weakn
How is X-linked myotubular myopathy-abnormal genitalia syndrome inherited?
X-linked myotubular myopathy-abnormal genitalia syndrome follows a x-linked recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does X-linked myotubular myopathy-abnormal genitalia syndrome typically begin?
Typical onset of X-linked myotubular myopathy-abnormal genitalia syndrome is neonatal. Age of onset can vary across affected individuals.