HANAC syndrome

Hereditary angiopathy with nephropathy, aneurysms, and muscle cramps (HANAC) syndrome is an autosomal dominant monogenic COL4A1-related disorder.

The exact prevalence is unknown.

The cardinal features of HANAC syndrome are helpfully described in the name of the condition:

  • hereditary angiopathy: small vessel disease of the brain, generally asymptomatic with no strokes 1-3
  • nephropathy: nephritis with haematuria, renal cysts may also be present (which may or may not be symptomatic) 1-3
  • aneurysms: intracranial aneurysms, generally are small do not rupture 1-3
  • muscle cramps: earliest manifestation and can affect any muscle 1-3

In addition to the HANAC features, and similar to COL4A1 brain small-vessel disease, additional body systems may also be involved, including the eyes (bilateral retinal artery tortuosity, cataracts, retinal haemorrhages), extra-cranial vasculature (Raynaud phenomenon), and heart (arrhythmias) 1-3.

HANAC syndrome is an autosomal dominant condition resulting from a mutation to the COL4A1 gene, located on the long arm of chromosome 13, that normally encodes for the alpha-1 chain of type IV collagen 1-3. Type IV collagen is an important component of basement membranes in many tissues, as demonstrated by the wide variety of body systems involved in this condition 1-3

Imaging is generally only remarkable for CNS manifestations 1-3.

CT is non-specific, demonstrating white matter regions of low attenuation 1,2.

MRI is the investigation of choice and demonstrates widespread confluent, bilateral, symmetric white matter hyperintensities on T2-weighted sequences, with relative sparing of subcortical U-fibers 1,2. There may be additional features less commonly seen, including dilated perivascular spaces and cerebral microhaemorrhages 2. Evidence of intracerebral macrohaemorrhage, ischaemic stroke, or porencephaly is generally not seen in HANAC syndrome 1,2.

Angiographic studies may demonstrate the presence of intracranial cerebral aneurysms, most commonly affecting the intracranial portion of the internal carotid artery 1,2.

No specific disease-modifying treatment is currently available and symptomatic management and specialist screening is recommended 1.

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rID: 55940
Tag: cases
Synonyms or Alternate Spellings:
  • Hereditary angiopathy, nephropathy, aneurysms, and muscle cramps syndrome
  • Hereditary angiopathy, nephropathy, aneurysms, and muscle cramps (HANAC) syndrome

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