OMIM ID:
HELIX Syndrome
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Alacrimia has been confirmed with Schirmer test strips but the ocular examination has been described as otherwise normal.
Systemic Features
All patients have anhidrosis resulting in alacrima and xerostomia with heat intolerance. Nails and hair are normal. Muscle weakness, heart palpitations, and post-exertional cramping may be experienced with mild exercise beginning in the first decade. Polydipsia and polydipsia may be additional complaints. Severe dental enamel wear is often evident. The skin has a fine, white scaliness. Adolescent-onset nephrocalcinosis has been reported in some patients.
The majority of patients have elevated serum Mg++ levels. Mild renal failure occurs with loss of NaCl and secondary hyperaldosteronism and hypokalemia.
Genetics
Inheritance
Homozygous mutations in the CLDN10 gene (13q32.1) are responsible for this disorder. Consanguinity is present in some families.
Pedigree
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.