enamel hypoplasia

Heimler Syndrome 1

Clinical Characteristics
Ocular Features: 

Some patients have mottling of the retinal pigment and features of macular dystrophy.

Systemic Features: 

Primary dentition seems to be normal but secondary teeth have generalized enamel hypoplasia.  Severe bilateral sensorineural hearing loss has been diagnosed in the first or second year of life.  The toenails have transverse ridges (Beau lines) and the fingernails exhibit leukonychia.

Due to the small number of reported families, there is some uncertainty regarding the specificity of the clinical features among the Heimler 1 and Heimler 2 syndromes.

Genetics

Biallelic mutations in the PEX1 gene (7q21.2) are responsible for this syndrome.

Heimler Syndrome 2 (616617) seems to be a unique disorder of peroxisome biogenesis resulting from biallelic mutations in the PEX6 gene.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

No treatment has been reported.

References
Article Title: 

Spectrum of PEX1 and PEX6 variants in Heimler syndrome

Smith CE, Poulter JA, Levin AV, Capasso JE, Price S, Ben-Yosef T, Sharony R, Newman WG, Shore RC, Brookes SJ, Mighell AJ, Inglehearn CF. Spectrum of PEX1 and PEX6 variants in Heimler syndrome. Eur J Hum Genet. 2016 Nov;24(11):1565-1571.

PubMed ID: 
27302843

Heimler Syndrome Is Caused by Hypomorphic Mutations in the Peroxisome-Biogenesis Genes PEX1 and PEX6

Ratbi I, Falkenberg KD, Sommen M, Al-Sheqaih N, Guaoua S, Vandeweyer G, Urquhart JE, Chandler KE, Williams SG, Roberts NA, El Alloussi M, Black GC, Ferdinandusse S, Ramdi H, Heimler A, Fryer A, Lynch SA, Cooper N, Ong KR, Smith CE, Inglehearn CF, Mighell AJ, Elcock C, Poulter JA, Tischkowitz M, Davies SJ, Sefiani A, Mironov AA, Newman WG, Waterham HR, Van Camp G. Heimler Syndrome Is Caused by Hypomorphic Mutations in the Peroxisome-Biogenesis Genes PEX1 and PEX6. Am J Hum Genet. 2015 Oct 1;97(4):535-45.

PubMed ID: 
26387595

Macular dystrophy in Heimler syndrome

Lima LH, Barbazetto IA, Chen R, Yannuzzi LA, Tsang SH, Spaide RF. Macular dystrophy in Heimler syndrome. Ophthalmic Genet. 2011 Jun;32(2):97-100.

PubMed ID: 
21366429

Keratosis Follicularis Spinulosa Decalvans, AD

Clinical Characteristics
Ocular Features: 

This genodermatosis has signs and symptoms beginning in childhood.  Photophobia is a prominent symptom.  The eyebrows and eyelashes are thin and sparse.  Recurrent blepharitis and keratitis are often present.

Systemic Features: 

The scalp is often dry and scaly.  Scalp alopecia begins sometime in the first two decades of life and becomes a major complaint by the third or fourth decade.  The face and especially the cheeks are often erythematous.  The scalp can have multiple follicular pustules which are most prominent in the occipital and nuchal areas.  Follicular keratotic papules are often located on the trunk and extensor areas of the limbs.  Histology of scalp skin biopsies show epidermal hyperplasia and an extensive perifollicular inflammatory infiltrate.

Enamel hypoplasia result in multiple and recurrent caries and loss of teeth.  The nails are often dystrophic.

Genetics

This is likely an autosomal dominant disorder based on the transmission pattern of several reported families but no locus or mutation has been reported.

There is also an X-linked form of Keratosis Follicularis Spinulosa Decalvans (KFSDX) (308800) which is more common.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Dental surveillance and treatment are important.  Ocular lubrication can be helpful in severe cases and ophthalmic topical antibiotics may be useful in treatment of blepharitis and keratitis.Clinica

References
Article Title: 

Heimler Syndrome 2

Clinical Characteristics
Ocular Features: 

Several cases have been reported with macular dystrophy and 'salt-and-pepper' mottling of the RPE extending to the midperiphery with foveal sparing.  Autofluorescence with hyper- and hypo-autofluorescent dots has been observed in the mottled areas of the RPE.  Spectral domain OCT has shown loss of the inner/outer segment boundary with RPE thinning and multiple retinal cysts but the ERG does not show rod-cone dysfunction. Visual acuity and the ocular fundus were normal in one patient until the age of 29 years when her vision dropped to 20/200 in one eye and 20/40 in the other.

Systemic Features: 

Primary dentition may be normal but secondary teeth have enamel hypoplasia (amelogenesis imperfecta).  The nails have Beau lines (transverse ridges) and leukonychia (white spots).  Severe sensorineural hearing loss develops sometime in the first year or two of life and it may be unilateral. At least one patient was documented to have had normal audiological test results until the age of 3 years.

Psychomotor development is normal at least until sensory deprivation occurs.

Genetics

This is a rare syndrome of ectodermally derived tissue which results from compound heterozygous mutations in the PEX6 gene (6p21.1).  A pair of monozygotic twin girls with this syndrome has been reported.  Parents are phenotypically normal.  No instance of parent-to-child transmission has been noted and it seems likely that this is an autosomal recessive disorder.

Another form of Heimler syndrome (234580) but with compound heterozygous mutations in the PEX1 gene (7q21.2) has been reported.

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

One patient has been treated with carbonic anhydrase inhibitors with apparent stabilization of vision.  Low vision aids and assistive hearing devices are likely of benefit for at least some patients.

References
Article Title: 

Spectrum of PEX1 and PEX6 variants in Heimler syndrome

Smith CE, Poulter JA, Levin AV, Capasso JE, Price S, Ben-Yosef T, Sharony R, Newman WG, Shore RC, Brookes SJ, Mighell AJ, Inglehearn CF. Spectrum of PEX1 and PEX6 variants in Heimler syndrome. Eur J Hum Genet. 2016 Nov;24(11):1565-1571.

PubMed ID: 
27302843

Macular dystrophy in Heimler syndrome

Lima LH, Barbazetto IA, Chen R, Yannuzzi LA, Tsang SH, Spaide RF. Macular dystrophy in Heimler syndrome. Ophthalmic Genet. 2011 Jun;32(2):97-100.

PubMed ID: 
21366429

Tuberous Sclerosis 1

Clinical Characteristics
Ocular Features: 

The primary clinical characteristic of tuberous sclerosis of both types 1 and 2 are the occurrence of hamartomas at multiple anatomic sites.  Ocular lesions include those of the eyelids which often appear in early childhood along with other facial angiofibromas (formerly called adenoma sebaceum).  Of greater clinical significance are lesions of the optic nerve and retina reported in about 75% of patients.  The latter (astrocytic hamartomas) may appear as mulberry-like growths typically located in the peripapillary area or as flat translucent lesions located more peripherally.  These are usually static but aggressive growth with retinal detachment and neovascular glaucoma requiring enucleation has been reported in several patients.  Calcification of these lesions may occur in utero or early in life.  These are seldom of clinical significance although optic atrophy has been reported. The iris may have hypopigmented areas.

Systemic Features: 

Hamartomas develop throughout the body in many organs such as the skin, brain, eye, kidney, and heart.  Ninety per cent of patients have skin lesions, including hypomelanotic patches called 'ashleaf' spots that can best be visualized under a Woods lamp.  Symptoms vary widely depending upon the location and size of the growths.  These appear as rhabdomyomas in the heart, angiomyolipomas in the kidneys, bone cysts, and oral fibromas.  Other intracranial growths such as subependymal astrocytomas and cortical tubers are evidence of CNS involvement that can interfere with brain function leading to seizures (in 80% of patients) and subnormal intellectual abilities (60-70% patients) as manifested by learning difficulties, subnormal IQs, as well as social and communication difficulties.   Hypoplasia of dental enamel with pitting in permanent teeth is seen in the majority of patients.  Some progression of tumor size and symptoms may occur.  Most hamartomas are benign but renal carcinoma has been reported in some patients.

Genetics

Many cases (two-thirds) occur sporadically but numerous reported pedigrees are consistent with autosomal dominant inheritance.  Type 1 TSC is caused by mutations in the TSC1 gene (9p34) encoding hamartin and is responsible for the disorder in about 25% of patients.

A more severe phenotype, tuberous sclerosis 2 (613254), is caused by mutations in the TSC2 gene on chromosome 16p13.3 and accounts for the majority of cases of tuberous sclerosis complex.  Genotyping is necessary to determine which mutation is responsible for the TS complex in each case as the phenotypic differences are inadequate to distinguish clinically between types 1 and 2.

New mutations are responsible for 50-70% of cases.

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

No effective preventative treatment exists but individual lesions can be surgically removed when indicated.

References
Article Title: 

Identification of the tuberous sclerosis gene TSC1 on chromosome 9q34

van Slegtenhorst M, de Hoogt R, Hermans C, Nellist M, Janssen B, Verhoef S, Lindhout D, van den Ouweland A, Halley D, Young J, Burley M, Jeremiah S, Woodward K, Nahmias J, Fox M, Ekong R, Osborne J, Wolfe J, Povey S, Snell RG, Cheadle JP, Jones AC, Tachataki M, Ravine D, Sampson JR, Reeve MP, Richardson P, Wilmer F, Munro C, Hawkins TL, Sepp T, Ali JB, Ward S, Green AJ, Yates JR, Kwiatkowska J, Henske EP, Short MP, Haines JH, Jozwiak S, Kwiatkowski DJ. Identification of the tuberous sclerosis gene TSC1 on chromosome 9q34. Science. 1997 Aug 8;277(5327):805-8.

PubMed ID: 
9242607

Tuberous sclerosis

Curatolo P, Bombardieri R, Jozwiak S. Tuberous sclerosis. Lancet. 2008 Aug 23;372(9639):657-68. Review.

PubMed ID: 
18722871
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