A 16-month-old girl is brought to the office by her mother due to breathing problems for the past month. The mother says, "She struggles to catch her breath when she gets excited. At other times, she seems to be holding her breath." The mother is also concerned that the patient, who started babbling and saying a few words after turning age 1, has spoken very little for the last few weeks. Medical history is significant for a simple febrile seizure at age 11 months and an upper respiratory tract infection 6 weeks ago. Family history is significant for a learning disorder in her older brother. On physical examination, the patient has a brief period of hyperventilation followed by hypoventilation, which passes within 30 seconds. Vital signs are otherwise normal. The patient makes brief eye contact with the physician but rocks back and forth and says nothing. She repeatedly twists her fingers and has an unsteady gait. This patient would most likely exhibit which of the following features?

Question

A 16-month-old girl is brought to the office by her mother due to breathing problems for the past month.  The mother says, "She struggles to catch her breath when she gets excited.  At other times, she seems to be holding her breath."  The mother is also concerned that the patient, who started babbling and saying a few words after turning age 1, has spoken very little for the last few weeks.  Medical history is significant for a simple febrile seizure at age 11 months and an upper respiratory tract infection 6 weeks ago.  Family history is significant for a learning disorder in her older brother.  On physical examination, the patient has a brief period of hyperventilation followed by hypoventilation, which passes within 30 seconds.  Vital signs are otherwise normal.  The patient makes brief eye contact with the physician but rocks back and forth and says nothing.  She repeatedly twists her fingers and has an unsteady gait.  This patient would most likely exhibit which of the following features?

Quizplus · Accepted Answer

11ec25c8_d6fb_6819_bc81_83b2325bebb4_MD0003_00 This child's respiratory abnormalities, loss of verbal skills, repetitive movements, and gait disturbance are suggestive of Rett syndrome (RS). RS is a genetic disorder characterized by normal development until age 6-18 months, when regression of speech, loss of purposeful hand movements (eg, twisting of fingers), development of stereotypical movements (eg, rocking back and forth), and gait abnormalities occur. Periodic breathing abnormalities, as seen in this patient, are common in RS and most likely caused by abnormal neuronal development and signaling within the medullary respiratory center. Alternating episodes of hyperventilation and hypoventilation tend to occur during periods of heightened emotion and are often associated with stereotypical movements. Other characteristic features of RS include early deceleration of head growth, resulting in microcephaly, autistic behaviors, and seizures. (Choice A) Dilated cardiomyopathy is a feature of Duchenne muscular dystrophy, a genetic disorder that can present with gait abnormalities due to weakness but is not associated with intermittent breathing problems, repetitive movements, or speech regression. The increased incidence of sudden death in RS is related to cardiac electrical instability from autonomic dysregulation, not dilated cardiomyopathy. (Choice B) A happy demeanor is characteristic of Angelman syndrome, a neurodevelopmental disorder caused by the absence of the maternally inherited copy of the UBE3A gene. Patients can have repetitive hand flapping, a jerky gait, and seizures; however, developmental delay, rather than regression, is typical, and hyperventilation-hypoventilation episodes are not associated with this condition. (Choice D) A musty odor is associated with phenylketonuria (PKU), an autosomal recessive metabolic disorder caused by phenylalanine hydroxylase deficiency. Untreated PKU causes intellectual disability, seizures, and skin abnormalities in early infancy. A period of normal development and intermittent breathing disturbances would not be seen. (Choice E) Ophthalmologic abnormalities are not characteristic of RS. A cherry-red macula is seen with Tay-Sachs disease, a lysosomal storage disease that causes neurodevelopmental regression, particularly of motor skills, but not repetitive hand movements or episodic breathing problems. Educational objective: Rett syndrome is characterized by a period of normal development followed by regression of speech, loss of purposeful hand use, stereotypical movements, and gait disturbance. Other features include early deceleration in head growth (ie, microcephaly), breathing abnormalities, autistic behaviors, and seizures. References: Rett syndrome: disruption of epigenetic control of postnatal neurological functions. (http://www.ncbi.nlm.nih.gov/pubmed/26060191) The course of awake breathing disturbances across the lifespan in Rett syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/29657083)

A 16-Month-Old Girl Is Brought to the Office by Her