CNTNAP1 mutations cause CNS hypomyelination and neuropathy with or without arthrogryposis.

OBJECTIVE: To explore the phenotypic spectrum and pathophysiology of human disease deriving from mutations in the CNTNAP1 gene. METHODS: In a field study on consanguineous Palestinian families, we identified 3 patients carrying homozygous mutations in the CNTNAP1 gene using whole-exome sequencing. An unrelated Irish family was detected by screening the GENESIS database for further CNTNAP1 mutations. Neurophysiology, MRI, and nerve biopsy including electron microscopy were performed for deep phenotyping. RESULTS: We identified 3 novel CNTNAP1 mutations in 5 patients from 2 families: c.2015G>A:p.(Trp672*) in a homozygous state in family 1 and c.2011C>T:p.(Gln671*) in a compound heterozygous state with c.2290C>T:p.(Arg764Cys) in family 2. Affected patients suffered from a severe CNS disorder with hypomyelinating leukodystrophy and peripheral neuropathy of sensory-motor type. Arthrogryposis was present in 2 patients but absent in 3 patients. Brain MRI demonstrated severe hypomyelination and secondary cerebral and cerebellar atrophy as well as a mega cisterna magna and corpus callosum hypoplasia. Nerve biopsy revealed very distinct features with lack of transverse bands at the paranodes and widened paranodal junctional gaps. CONCLUSIONS: CNTNAP1 mutations have recently been linked to patients with arthrogryposis multiplex congenita. However, we show that arthrogryposis is not an obligate feature. CNTNAP1-related disorders are foremost severe hypomyelinating disorders of the CNS and the peripheral nervous system. The pathology is partly explained by the involvement of CNTNAP1 in the proper formation and preservation of paranodal junctions and partly by the assumed role of CNTNAP1 as a key regulator in the development of the cerebral cortex.

Extreme clinical variability of dilated cardiomyopathy in two siblings with Alström syndrome.

Alström syndrome (ALMS) is a rare autosomal recessive disorder caused by mutations in the ALMS1 gene. We report two brothers, 3 and 4 years of age and diagnosed with ALMS, who initially presented in infancy with severe dilated cardiomyopathy during febrile respiratory infection. The disease course in the two siblings was marked by significant intrafamilial variability. Although cardiomyopathy in the older sibling has mainly resolved thus allowing for the discontinuation of medical therapy, heart function in the younger sibling continues to deteriorate despite maximal drug support with furosemide, carvedilol, captopril, and aldospirone. Genetic analysis revealed homozygous mutations, c.8008C>T (R2670X), in ALMS1 resulting in premature protein truncation. This report further emphasizes the exceptional intrafamilial variability of ALMS, mainly during the natural course of cardiac disease.

[The relationship between RSV bronchiolitis and the development of asthma].

Respiratory syncytial virus (RSV) is the most common cause of bronchiolitis during infancy and is associated with subsequent wheezing and asthma, but the nature of this association is not fully understood. In that sense, RSV bronchiolitis may serve as a marker, reflecting predisposition of the individual for virus-induced wheezing early in life and/ or asthma later in life. This review discusses existing data on RSV infection and respiratory complications later in life, as well as the link between RSV and asthma.