Question: List two common features of Tay syndrome.

Context:
TTD is part of a more broadly defined group of diseases identified as IBIDS (ichthyosis, brittle hair, impaired intelligence, decreased fertility and short stature). Photosensitive cases are also identified as PIBIDS (photosensitivity with IBIDS). Cases without manifest ichthyosis are also identified as PBIDS. These syndromes defy rigorous definition because of clinical variation between patients. The original two cases were described by Tay in oriental siblings, whose parents were first cousins; thus the disease is also known as Tay syndrome. 
Tay syndrome or IBIDS is a rare autosomal recessive genetic disorder characterized by congenital ichthyosis and abnormal brittle hair (trichothiodystrophy). Other features include photosensitivity, abnormal nails and multiple developmental defects affecting organs mainly derived from neuroectoderm. 
We report a case of trichothiodystrophy initially classified as Tay syndrome that based on clinical features, complementary exams as well as on the disease evolution was labelled as PIBIDS syndrome.
Tay-syndrome is a rare monogen-inherited ektodermal dysplastic syndrome with ichtyosis, fragility of the hair and physical and mental retardation. The congenital ichtyosis is ubiquitous. Only the skin on the flexion side of the extremity joints are not involved (orthocerathosis combined with paraceratotic strings).
In Tay syndrome, the trichothiodystrophy is accompanied by congenital ichthyosis, short stature, delayed physical and mental development and pyramidal tract signs with increase in muscular tone and brisk tendon reflexes. 
We present a case of Tay syndrome in which a cranial MRI revealed an almost total lack of myelin within the cerebral hemispheres and a patchy hypomyelination of the cerebellum. In accordance, a strongly prolonged visual evoked response pointed to a dysfunction of the white matter in Tay syndrome.
For example, the brittle hair due to sulphur deficiency (trichothiodystrophy) is nowadays regarded as genetically heterogeneous; three different syndromes can be distinguished: BIDS syndrome, Tay syndrome, and PIBIDS syndrome. 
The Tay syndrome (congenital ichthyosis with trichothiodystrophy).
The Tay syndrome is a distinct type of congenital ichthyosis characterized by a peculiar anomaly of hair growth which has been termed trichothiodystrophy. 
Other features of this syndrome are low birth weight, short stature, mental retardation, delayed neuromuscular development and other CNS anomalies, dysplasia of nails, hypoplasia of subcutaneous fatty tissue, prematurely aged facial appearance, hypogonadism, cataracts, osteosclerosis, dysphonia, and increased susceptibility to infections. 

Answer: Tay syndrome is a rare autosomal recessive genetic disorder characterized by congenital ichthyosis and trichothiodystrophy (abnormal brittle hair). Other less common features of this syndrome are photosensitivity, low birth weight, short stature, mental retardation, delayed neuromuscular development and other CNS anomalies, dysplasia of nails, hypoplasia of subcutaneous fatty tissue, prematurely aged facial appearance, hypogonadism, cataracts, osteosclerosis, dysphonia, and increased susceptibility to infections.
Exact answer: ichthyosis, trichothiodystrophy